CMP Journal 2026-07-13
Statistics
Nature: 1
Nature Materials: 1
Nature Nanotechnology: 1
Nature Physics: 2
arXiv: 64
Nature
Perovskite-organic tandem solar cells with a photo-transformable stabilizer
Original Paper | Solar cells | 2026-07-12 20:00 EDT
Ruihan Wu, Shucheng Qin, Tianwei Zou, Xin Jiang, Senyao Wang, Siyu Zhuang, Hongyu Li, Yiyang Wang, Siguang Li, Minchao Liu, Yishun Feng, Yufei Gong, Haozhe He, Peiwen Liao, Yu Chen, Jinyuan Zhang, Xiaojun Li, Lei Meng, Yongfang Li
Wide-bandgap (WBG) mixed-halide perovskites with high Br content, which are employed as the front cell material in perovskite-organic tandem solar cells (TSCs), often suffer from initial halide-mixing inhomogeneity and light-induced halide segregation1-3, limiting the performance of perovskite-organic TSCs. Here, we introduced a photo-transformable additive 4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzylamine (TDB) into the WBG perovskite precursor solution to establish a two-stage strategy for stabilizing the mixed-halide phase. During crystallization, TDB improves the initial halide homogeneity by suppressing the rapid precipitation of the Br-rich phase and accelerating halide mixing upon annealing. During operational illumination, TDB undergoes transformation to form a new species with stronger adsorption on the perovskite grain-boundary surfaces, which inhibits the formation of iodide-related defects, suppresses defect-assisted carrier trapping and ion migration, thereby mitigating light-induced halide segregation4-6. The representative WBG perovskite (Eg = 1.88 eV) solar cell achieved a power conversion efficiency (PCE) of 20.01%, with an open-circuit voltage of 1.42 V, a fill factor of 85.13% and improved stability under illumination. By integrating the WBG perovskite solar cell into a monolithic perovskite-organic TSC, we achieved a PCE of 28.80% with a certified steady-state PCE of 28.04%. The perovskite-organic TSC retained 90% of its initial PCE after 625 h of operation under the ISOS-L-1 protocol.
Solar cells
Nature Materials
Unconventional skyrmions in synthetic antiferromagnets
Original Paper | Ferromagnetism | 2026-07-12 20:00 EDT
Kayla Fallon, Reshma Peremadathil-Pradeep, Christopher E. A. Barker, Zoey Tumbleson, Emily Darwin, Andrea Meo, Eloi Haltz, Benjamin A. Brereton, Trevor Almeida, Colin Kirkbride, Sara Villa, Sophie A. Morley, Mario Carpentieri, Riccardo Tomasello, Hans J. Hug, Christopher H. Marrows, Stephen McVitie
Magnetic skyrmions are topologically protected spin textures that can act as reconfigurable nanoscale information carriers. In synthetic antiferromagnets, interlayer exchange coupling provides a control parameter beyond the interfacial Dzyaloshinskii-Moriya interaction and magnetic anisotropy. Here we engineer a synthetic antiferromagnet of two chemically distinct ferromagnets, CoB and CoFeB, in which the external field and interlayer exchange act asymmetrically on the sublattices. Their competition, acting as an effective field, gives rise to two skyrmion families in different field regimes: conventional-polarity skyrmions at large fields, and inverse-polarity skyrmions at smaller fields, where the effective field reverses sign. Using element-resolved X-ray magnetometry, correlative magnetic force and Lorentz transmission electron microscopies, and micromagnetic modelling, we show that all textures reside solely in the CoFeB layers, driven by a Ruderman-Kittel-Kasuya-Yosida exchange field from the CoB layers. This effective-field route enables programmable three-dimensional spin textures with layer-selected polarity for skyrmion-based computing.
Ferromagnetism, Magnetic properties and materials, Surfaces, interfaces and thin films
Nature Nanotechnology
Nanoengineered doping overcomes sintering and grain-boundary limitations in all-solid-state lithium batteries with garnet electrolytes
Original Paper | Batteries | 2026-07-12 20:00 EDT
Yijie Liu, Weiran Zhang, Zeyi Wang, Jianchun Rao, Bhuvsmita Bhargava, Hongli Wan, Tengrui Wang, Zhengwu Fang, Xiyue Zhang, Nan Zhang, Zheng Li, Xinzi He, Caitlin M. Quinn, Miaofang Chi, Fu Chen, Paul Albertus, Chunsheng Wang
Li6.5La3Zr1.5Ta0.5O12 (LLZTO) garnet material is a promising inorganic electrolyte for all-solid-state lithium metal batteries because of its safety, broad electrochemical stability and low air sensitivity. However, LLZTO faces critical challenges related to sintering and grain boundaries that adversely affect its mechanical and electrochemical properties. Here we propose oversaturation doping of yttrium into Li6.72La3.00Y0.22Zr1.28Ta0.50O12 (LLYZTO) using 1.0 wt% of (Y2O3)0.08(ZrO2)0.92 (YSZ). During annealing, a La-Y-O (LYO) nanoscale interphase forms at the grain boundaries. This material nanoengineering approach improves indentation fracture toughness, increases the critical current density and enhances bulk ionic conductivity while maintaining low electronic conductivity. The LLYZTO with 1.0 wt% of YSZ (LLYZTO-1.0 wt% YSZ) is more lithiophobic than its undoped counterpart, and accommodates the volume changes of LiCoO2 during battery operation, enabling a 2.2 mAh cm-2 all-solid-state Li||LiCoO2 coin cell to deliver 2.0 mAh cm-2 at 0.66 mA cm-2 for over 100 cycles at 30 °C and 1 MPa of stack pressure. The fracture toughness of LLYZTO-1.0 wt% YSZ also allows the sintering fabrication of a square 5.29-cm2 and 150 µm-thick electrolyte membrane, which can be effectively used in lab-scale Li||LiCoO2 pouch cells. We also demonstrate the extension of the LYO interphase approach to other Li-based inorganic solid electrolytes.
Batteries, Materials for energy and catalysis, Microscopy, Synthesis and processing
Nature Physics
Emergence of phase coherence in a magnon Bose-Einstein condensate
Original Paper | Bose-Einstein condensates | 2026-07-12 20:00 EDT
Malte Koster, Matthias R. Schweizer, Timo Noack, Vitaliy I. Vasyuchka, Dmytro A. Bozhko, Burkard Hillebrands, Mathias Weiler, Alexander A. Serga, Georg von Freymann
The spontaneous emergence of coherence is a defining feature of multibody quantum systems, underlying phenomena from superconductivity to quantum information processing. Although Bose-Einstein condensates provide a unique setting for studying this process, direct observation of how a condensate acquires a coherent global phase has remained challenging. Here we provide evidence of spontaneous phase formation in a magnon Bose-Einstein condensate. Using a phase-referenced detection technique, we track the phase of the condensate coherent state relative to an external reference, revealing how an initially incoherent magnon gas thermalizes and undergoes a spontaneous transition into a coherent quantum state with a well-defined macroscopic phase. This observation provides evidence of spontaneous symmetry breaking in a quasiparticle condensate, confirming a central prediction of Bose-Einstein condensation theory that extends across diverse quantum systems.
Bose-Einstein condensates, Magnetic properties and materials
Error correction of a logical qubit encoded in a single atomic ion
Original Paper | Atomic and molecular physics | 2026-07-12 20:00 EDT
Kyle DeBry, Nadine Meister, Agustin Valdes Martinez, Colin D. Bruzewicz, Xiaoyang Shi, David Reens, Robert McConnell, Isaac L. Chuang, John Chiaverini
Quantum error correction is essential for quantum computers to run useful algorithms, but large-scale fault-tolerant computation remains limited by requirements for operation fidelity and the number of controllable qubits. Traditional schemes encode each logical qubit into multiple physical qubits, increasing resource demands and complexity. Recent theoretical work has proposed a complementary approach that performs error correction at the level of single qubits by using additional internal quantum states, which could reduce overhead. This approach has not yet been demonstrated experimentally, partly due to the difficulty of performing error measurements and subsequent error correction with high fidelity. Here we demonstrate a quantum error-correction protocol in a single atomic ion that reduces errors by up to a factor of 2.2 and extends the qubit lifetime by a factor of up to 1.5 compared with an unencoded qubit. We encode the qubit in spin-cat logical states and implement an autonomous correction scheme that operates without mid-circuit measurements of an ancilla. The approach is applicable to a range of finite-dimensional quantum platforms and could serve either as a component of larger error-correction codes or as a standalone strategy in few-qubit devices such as quantum network nodes.
Atomic and molecular physics, Quantum information, Qubits
arXiv
Brownian Bridge for Coherent State Path Integral Monte Carlo
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
We propose a new Brownian bridge construction for our newly devised Coherent States Path Integral Monte Carlo algorithm. We apply it to the numerically exact calculation of the thermodynamic properties of the Helium fluid on a plane at low non zero temperature. We find very good agreement with the conventional plane waves path integral Monte Carlo results.
Statistical Mechanics (cond-mat.stat-mech), Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
8 pages, 8 tables
Energetics of fractional anomalous Hall crystals in rhombohedral graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
Félix Desrochers, Ashvin Vishwanath
Fractional anomalous Hall crystals (FAHCs) replicate the topological order of the fractional quantum Hall effect in the continuum without requiring any external magnetic field. They spontaneously break continuous translation symmetry like a Wigner crystal, but are distinguished by each unit cell holding a fixed fractional number of electrons. Until now, these states have been confined to theoretical speculation or engineered models, leaving open the question of whether they can plausibly emerge in actual physical systems. Here, we establish them as energetically competitive candidate states in a realistic material setting. We study rhombohedral pentalayer graphene (R5G) with variational wavefunctions that are exact zero modes of a recently proposed ideal model of R5G. We evaluate their energies using Monte Carlo, after reinstating realistic dispersion and screened Coulomb interactions. We find FAHCs to be energetically competitive with integer anomalous Hall crystals and Fermi liquids, and their stability follows a simple principle. Each crystal maps onto a parent quantum Hall liquid that fixes its interaction energy, while the kinetic energy favors crystal periods that match the finite-momentum minimum of R5G’s Mexican-hat dispersion. A weak periodic potential can then selectively lower and pin the commensurate fractional crystals. This picture predicts how the integer and fractional quantum anomalous Hall stability windows evolve with twist angle and displacement field, which we compare to recent experiments. These results support a continuum-and-interactions-first route to fractional anomalous Hall states in rhombohedral graphene.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 + 39 pages, 8 + 8 figures
Quantum Oscillation Signatures of $\mathbb{Z}_2$ Monopole Charge in Nodal-Ring Semimetals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Aravind Karthigeyan, Yoonseok Hwang, Bohm-Jung Yang, Junyeong Ahn
Topological semimetals host band nodes characterized by quantized invariants that can appear in bulk responses, yet some invariants remain hidden from standard probes. In particular, band nodes can carry secondary topological charges whose transport signatures are still largely unexplored. Here we study three-dimensional nodal-line semimetals in which nodal rings carry both the Berry phase $ w_1\pi$ and a $ \mathbb{Z}_2$ monopole charge $ w_2$ . We show that magnetic quantum oscillations, usually treated as a probe of $ w_1$ , can directly diagnose $ w_2$ , with the relevant signal selected by the magnetic-field direction. For a field along the ring axis, the inner and outer extremal orbits of the toroidal Fermi surface both encircle the $ w_2$ -enforced thread and exhibit a topological phase shift $ \nu w_2\pi$ in the $ \nu$ th harmonic, which is accessible through standard phase-resolved quantum-oscillation analysis. By contrast, for a field applied perpendicular to the ring axis, the relevant extremal orbit exhibits the usual $ \pi$ phase shift associated with the Berry phase $ w_1\pi$ , independent of $ w_2$ . For weak doping, three-dimensional ABC-stacked graphdiyne is predicted to exhibit the proposed oscillations in a field range accessible with present-day high-field facilities.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 4 figures; Supplemental Material: 70 pages, 5 figures
The monopole plasma resonance: a smoking gun of 3D $U(1)$ quantum spin liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
Anish Koley, Saranyo Moitra, Inti Sodemann Villadiego
Certain 3D $ U(1)$ spin liquids, such as those arising in dipolar quantum spin ice, have an emergent monopole which is the source of an emergent magnetic field that transforms under symmetries like an electric polarization. As a consequence, these monopoles carry a physical electric charge in their cores and form a plasma at low temperatures. Due to the monopole coupling to emergent gauge fields, the full system behaves as an electrical insulator for DC transport, but can display a sharp plasma resonance analogous to a metal at very low frequencies. This can serve as a clear fingerprint to detect these states in materials. We discuss the optimal conditions to observe this phenomenon in the 3D $ U(1)$ spin-liquid candidate Ce$ _2$ Zr$ _2$ O$ _7$ .
Strongly Correlated Electrons (cond-mat.str-el)
4+16 Pages, 2+4 Figures
Exact Lindbladian Dynamics from Conformal Embeddings and Topological Defects in Conformal Field Theory
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
Analyzing the dynamics of physical observables in open quantum many-body systems is a fundamental but highly challenging task that has yielded very few exact results. In this work, we identify intrinsic conformal structures that restore exact solvability in $ (1+1)$ D conformal field theories. For $ N$ Majorana fermions with linear mode jumps, the adjoint Lindbladian is triangular on reduced even Majorana monomials, yielding recursive exact Heisenberg evolution. In Wess-Zumino-Witten models admitting conformal Majorana embeddings, this hierarchy gives exact dynamics of affine-current products realized as Majorana bilinears, including regimes where the Kac-Moody current algebra alone does not close. In diagonal rational conformal field theories, Verlinde topological defect lines furnish jump operators whose primary-sector dynamics is exactly diagonal: topological-charge probabilities are conserved, while intersector coherences dephase at rates fixed by the modular $ S$ matrix and nonnegative measurement strengths. These examples show that intrinsic conformal structures, such as conformal embeddings and modular data, can organize exactly solvable open conformal dynamics.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
8+22 pages
Magnetic Field Control of the Néel Vector and Magnon Visibility in Altermagnetic MnTe
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
Tobias Weber, Niclas Heinsdorf, Shane Smolenski, Sawyer Beltz, Alexandre Ivanov, Andrea Piovano, Victor Mecoli, Sean Knapp, Ruiqi Tang, Amir Henderson, A. K. M. Ashiquzzaman Shawon, Taylor Pierce-James, Na Hyun Jo, Denis Karaiskaj
Altermagnetic order gives rise to momentum-dependent spin splitting of electronic and magnonic excitations even in the absence of a net magnetization. Here, we investigate the magnetic field dependence of the spin-wave spectrum of altermagnetic $ \alpha$ -MnTe using inelastic neutron scattering and linear spin-wave theory. An in-plane magnetic field continuously reorients the Néel vector by overcoming the weak crystalline anisotropy, while remaining small compared with the dominant exchange scale. We find that this reorientation leaves the magnon energies and line widths essentially unchanged, but strongly modifies the measured spectral intensity through the transverse-momentum projection. Our results demonstrate a clear separation between the soft orientational degree of freedom of the antiferromagnetic order and the robust exchange-dominated chiral magnon spectrum. This combination establishes $ \alpha$ -MnTe as a platform for reconfigurable magnon coupling, in which external fields tune how excitations interact with polarized probes without substantially altering their frequency or coherence.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 5 figures
Fermion-mediated Casimir effect on mesoscopic rings implementing non-Clifford SWAP$^α$ gates
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Liang Du, Qing-Dong Jiang, Yijia Wu
The Casimir effect is typically governed by intrinsic material properties and lacks in situ tunability. We show that, in mesoscopic rings, both the magnitude and sign of the fermion-mediated Casimir interaction can be controlled via the Aharonov-Bohm effect. The resulting interplay between the Aharonov-Bohm phase and the Casimir interaction provides a route to engineer long-range interactions. In particular, this mechanism enables the implementation of non-Clifford SWAP$ ^{\alpha}$ gates between spatially separated spin qubits, thereby reducing the overhead for universal quantum computation and quantum error correction in spin-qubit architectures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 3 figures
Probing Cooper pair momentum by quasiparticle steering with planar Josephson junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Isidora Araya Day, Anton R. Akhmerov, Antonio R. L. Manesco
The Cooper pair momentum in a superconductor is associated with a phase gradient of the superconducting order parameter. In general, this momentum is small compared to the Fermi momentum, which makes it challenging to measure. Josephson junctions, however, enable the creation of large phase gradients and transfer of the Cooper pair momentum to quasiparticles via Andreev reflection. In this work we demonstrate that Andreev bound states propagating along ballistic planar Josephson junctions eject into an adjacent normal region at a phase-controlled angle that scales as $ \Theta \sim \sqrt{\Delta/ \mu}$ , where $ \Delta$ is the superconducting gap and $ \mu$ is the chemical potential. This angle parametrically exceeds the conventional Cooper pair momentum scale $ \Delta/ \mu$ , and thus this phenomenon is sizeable even within the Andreev approximation regime $ \Delta / \mu \ll 1$ . Our results establish phase-controlled quasiparticle ejection as a kinematic probe of condensate momentum transfer: unlike existing probes that detect the Doppler energy shift, the signal appears as a momentum-space deflection of emitted quasiparticles.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
21 pages, 6 figures
A strong-coupling theory for polarizable symmetrically charged walls with counterions only
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-13 20:00 EDT
Ladislav Šamaj, Alexandre P. dos Santos, Emmanuel Trizac
A pair of parallel polarizable planar walls at distance d is considered. The walls are symmetrically charged with a uniform surface charge density, neutralized by mobile point counterions moving between them. The case of repulsive particle images is studied in the strong-coupling (SC) regime. Of interest is the dependence of the effective inter-wall interaction (pressure), mediated by the mobile counterions, as a function of the distance d. It is shown that previous virial SC single-particle theories work well at small d when the dielectric jump is small; for intermediate and large dielectric jumps they are inadequate even in the SC region. Here, we propose a Wigner-type SC theory based on harmonic deviations of particles from their ground-state monolayer or bilayer Wigner structures formed inside the space between the dielectric walls. Our Monte-Carlo simulations are in very good agreement with the Wigner SC predictions, even down to moderate coupling constants ($ \Xi > 10$ ).
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
Ferroelastic instability in rutile TiO2 and thermodynamic suppression of the CaCl2-type phase
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Jared Pohlmann, Anjy-Joe Olatunbosun, Kenneth Park
We investigate the role of the CaCl2-type (Pnnm) phase in the high-pressure transformation of rutile TiO2, whose experimental signature has remained elusive. While analogies with other rutile-type oxides suggest such an intermediate, TiO2 typically exhibits a direct transformation to higher-coordination phases such as baddeleyite. Using an all-electron density functional framework combined with density functional perturbation theory, we show that rutile TiO2 undergoes a ferroelastic instability characterized by the development of an orthorhombic strain and a double-well energy landscape at 13.5 GPa. This instability is associated with the softening of the C11 - C12 elastic combination and the condensation of a B1g phonon mode, involving coordinated rotations of TiO6 octahedra that lower the symmetry to the Pnnm structure. Despite this clear elastic and dynamical pathway, enthalpy calculations show that the CaCl2-type phase is only weakly stabilized relative to rutile and remains energetically unfavorable compared to competing columbite and baddeleyite phases. Consequently, the Pnnm phase does not emerge as a stable high-pressure polymorph but instead exists as a transient or weakly metastable intermediate. These results demonstrate that the CaCl2-type phase represents the intrinsic ferroelastic response of rutile TiO2, yet is suppressed by thermodynamic competition, providing a consistent and unified explanation for its elusive experimental observation.
Materials Science (cond-mat.mtrl-sci)
Loop-current orderings in SU($N$) two-leg fermionic ladder through duality symmetries
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
M. Habchy, F. Rose, P. Lecheminant
We investigate the formation of loop-current ordered phases in half-filled SU($ N$ ) two-leg fermionic ladders. Using a low-energy approach, we uncover the existence of non-perturbative duality symmetries relating four competing orders. Two of these orders correspond to loop-current ordered phases that spontaneously break the time-reversal symmetry and describe charge currents circulating in a staggered pattern either around the plaquettes or along the diagonals of the ladder. These unconventional phases are shown to be dual to conventional (charge and bond) density-wave phases through an exact density-current duality symmetry existing on the lattice. From a perturbative renormalization group approach, we find that these phases for $ N>2$ are stabilized in a half-filled SU($ N$ ) two-leg Hubbard ladder with an additional SU($ N$ ) Hund’s interaction. The effect of a small doping on these phases is also discussed.
Strongly Correlated Electrons (cond-mat.str-el)
19 pages, 7 figures
Grain-boundary-mediated kinetic arrest in graphite-to-diamond transformation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Zuzanna Malinowska-Trzmielak, Vilmos Neuman, Mark Wilson
The graphite-to-diamond transition exhibits striking variability under high-pressure, high-temperature (HPHT) conditions, producing diamond, graphitic phases, or metastable, mixed diamond-graphite nanocomposites despite similar synthesis conditions. Existing atomistic models, largely based on idealised single-crystal graphite, do not explain the persistence of partially transformed intermediate states under HPHT conditions. Here, using large-scale molecular dynamics simulations, we show that precursor grain structure governs graphite-to-diamond transformation pathways by decoupling diamond nucleation from cooperative transformation propagation. Grain boundaries first facilitate local sp$ ^3$ nucleation, after which diamond growth propagates within individual grains but becomes arrested at crystallographically mismatched grain boundaries. As a result, structurally heterogeneous graphite stabilizes kinetically arrested mixed sp$ ^2$ -sp$ ^3$ states, whereas large or single-crystalline domains favour cooperative bulk transformation into diamond. Our findings identify structural heterogeneity as a missing control parameter alongside pressure and temperature, reframing metastable transformation products as kinetically trapped states arising from precursor microstructure rather than thermodynamic intermediates. Precursor crystallinity therefore emerges as a practical control parameter governing graphite-to-diamond transformation pathways.
Materials Science (cond-mat.mtrl-sci)
High density two-component glasses of organic semiconductors prepared by physical vapor deposition
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Yejung Lee, Shinian Cheng, M. D. Ediger
Physical Vapor Deposition (PVD) is widely utilized for the production of organic semiconductor devices due to its ability to form thin layers with exceptional properties. Although the layers in the device usually consist of two or more components, there is limited understanding about the fundamental characteristics of such multi-component vapor-deposited glasses. Here, spectroscopic ellipsometry was employed to characterize the densities, thermal stabilities and optical properties of co-vapor deposited NPD and TPD glasses across the entire range of composition. We find that co-deposited NPD and TPD form high density glasses with enhanced thermal stability. The dependences of density and stability upon substrate temperature are correlated, and the birefringence of the co-deposited glasses is determined by the reduced substrate temperature of mixtures. Additionally, we observe that the transformation of a highly stable and dense two component glass into its supercooled liquid initiates from the free surface and propagates into the bulk at constant velocity, like single component PVD glasses. All these features are consistent with the surface equilibration mechanism.
Materials Science (cond-mat.mtrl-sci)
25 pages, 5 figures, 51 references, Supporting Information (5 figures)
J. Phys. Chem. Lett. 2024, 15, 8085-8092
Generic behavior of ultrastability and anisotropic molecular packing in co-deposited organic semiconductor glass mixtures
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-13 20:00 EDT
Shinian Cheng, Yejung Lee, Junguang Yu, Lian Yu, Mark D. Ediger
Vapor-deposited glass mixtures of organic semiconductors commonly serve as active layers in organic electronic devices, whose lifetime and performance are strongly influenced by the stability and structure of these mixed glasses. Here, we study the stability and anisotropic molecular packing of six co-deposited organic semiconductor glass mixtures with 50:50 weight ratio, by differential scanning calorimetry and spectroscopic ellipsometry. We find that all six binary systems exhibit high kinetic stability and significantly reduced enthalpy relative to the corresponding liquid-cooled glassy mixtures (ultrastable behavior), even for systems where the glass transition temperatures of the components differ by more than 90 K. Furthermore, we demonstrate that the birefringence of a co-deposited glass mixture, a measure of its anisotropic packing, can be predicted from the birefringence of glasses of the two pure components. These results for stability and structure are expected to be applicable to other co-deposited organic semiconductor glass mixtures, so long as the two components mix well in the glass and individually can form ultrastable glasses. Therefore, our findings are significant for designing novel electronic devices with enhanced device lifetime and increased operational efficiency.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
5 figures, 27 pages, 51 references, Supplemental Information (6 figures)
Chem. Mater. 2024, 36, 3205-3214
Hybrid DiffractGPT-Rietveld Refinement Framework for Automated X-ray Diffraction Analysis
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Charles Rhys Campbell, Justin Ely, Jaehyung Lee, Frank M. Abel, Kamal Choudhary
X-ray diffraction (XRD) is fundamental to structural materials characterization, yet transforming a raw powder pattern into a refined crystal structure still demands considerable domain expertise. We present AGAPI-XRD, a hybrid framework integrating DiffractGPT generative structure prediction, database pattern matching against JARVIS-DFT and COD, and automated Rietveld refinement and ALIGNN-FF relaxation through a unified API at this https URL. First, we used the AGAPI-XRD pipeline to evaluate the crystal structure of a variety of minerals in the RRUFF database that were experimentally characterized using powder x-ray diffraction. Next, we benchmarked the lattice parameter prediction fidelity of the AGAPI-XRD pipeline using a subset of the Alexandria PBE-hull dataset and the subset of RRUFF minerals that have known lattice parameters. AGAPI-XRD returns valid lattice parameters for 79.7% of the RRUFF benchmark minerals and for 94.8–98.1% of the Alexandria subset, while identifying a candidate structure for 93.8% of RRUFF minerals. For this benchmark, pattern matching delivers the highest accuracy for known phases, while DiffractGPT extends structure generation to complex materials absent from existing databases. Together, AGAPI-XRD advances accessible, end-to-end automated crystal structure determination from powder XRD data.
Materials Science (cond-mat.mtrl-sci)
Interface-induced spin-resolved type-II band alignment and enhanced magnetic anisotropy in MSe2/WTe2 (M = V, Cr, Mn, Fe and Co) van der Waals heterobilayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Paras Poswal, Ranjit Pati, Neeraj Shukla
Two-dimensional van der Waals heterobilayers provide an attractive platform for the development of next-generation spintronic devices. Here, first-principles calculations are performed to investigate the structural, electronic and magnetic properties of MSe2/WTe2 (M = V, Cr, Mn, Fe, and Co) van der Waals heterobilayers. The pristine WSe2/WTe2 heterobilayer in AA’-configuration is found to be energetically favorable and exhibits type-II band alignment with a band gap of 0.70 eV, and this provides an ideal platform for controlling carrier transport. Substituting W with 3d transition metal atoms, induces long-range magnetic ordering and reconstructs the spin-resolved electronic band structure. The formation of the heterointerface generates pronounced charge redistribution and an intrinsic built-in electric field, leading to interface-induced electronic reconstruction. MnSe2/WTe2 heterobilayer exhibits half-metallicity, whereas FeSe2/WTe2 heterobilayer simultaneously exhibits half-metallicity and spin-resolved type-II band alignment. Interfacial electronic reconstruction further produces a substantial perpendicular magnetic anisotropy, driving MnSe2 from an in-plane easy axis with MAE value of 1.10 meV in the isolated monolayer to a robust out-of-plane easy axis with MAE value of 20.8 meV in the heterobilayer. Among all the structures, CoSe2/WTe2 heterobilayer exhibits maximum Curie temperature (273.87 K). The combined results establish that interface engineering makes MSe2/WTe2 heterobilayers as a promising candidates for next-generation low-dimensional spintronic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)
1-15 Page MAnuscript, 16-19 supporting Information,
Fast Homoepitaxy on (100) \b{eta}-Ga2O3 Substrates with Large Grown-In Offcut
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
M. Brooks Tellekamp, Drew Haven, David Joyce, John Mangum, Henry Garland, Robert Lavelle, Kevin Schulte, Anna Sacchi, Matt Young, Andriy Zakutayev
The choice of crystalline orientation and offcut angle is non-trivial for low-symmetry $ \beta\text{-Ga}_2\text{O}_3$ , where anisotropy impacts bulk and thin film synthesis, material properties, and power device fabrication and performance. Scalable (100)-oriented $ \beta\text{-Ga}_2\text{O}_3$ wafers are desirable for electronic devices but are not typically used due to 10-30x slower growth rates compared to other orientations. Here we report molecular beam epitaxy (MBE) growth rates equal to the fast growth direction by using (100) $ Ga_2O_3$ wafers with large grown-in offcuts. The offcuts (up to 13.4°) are directly grown by Edge-defined Film-fed Growth (EFG) of 2D ribbons with rotated seed crystals, avoiding material loss from crystal boule offcut methods while maintaining high crystalline quality. Chemical-mechanical polishing produces epitaxy-ready substrates, and step flow growth is observed across all offcut angles. We measure an unintentional n-type doping density of $ 2{\times}10^{15} cm^{-3}$ , one of the lowest values reported for MBE-grown films. Planar Schottky barrier diodes on these epilayers without edge termination have an on/off ratio ~10$ ^5$ and an average breakdown field of 1.56 MV/cm, comparable to or exceeding similar devices fabricated on other orientations. Overall, these results illustrate the importance of both crystal face and offcut angle and validate the use of the scalable (100)-oriented $ \beta\text{-Ga}_2\text{O}_3$ wafers.
Materials Science (cond-mat.mtrl-sci)
Structural Origin of Water Heat Capacity Anomaly from Classical and Quantum Simulations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
Kam-Tung Chan, Dylan A. Folkner, Margaret L. Berrens, Alexei A. Stuchebrukhov, Lee-Ping Wang, Davide Donadio
Water isobaric heat capacity is anomalously large under ambient conditions and exhibits a sharp maximum upon supercooling. Using classical and path-integral molecular dynamics with accurate machine-learning interatomic potentials, we show that nuclear quantum effects primarily act by suppressing high-frequency vibrations, while the anomalous temperature dependence of the isobaric heat capacity originates from structural fluctuations, quantified by the second-solvent-shell intruder order parameter. A simple two-state mapping reveals an effective enthalpy scale of about 4 kJ/mol associated with the interconversion of low- and high-density-like local structures, providing a microscopic link between their population changes and the excess heat capacity from supercooled to ambient conditions.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Main text and supporting information
Vacancy Effect on the Ground-State Energy of a Bose Gas Trapped by 1D Imperfect Artificial Crystal
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-07-13 20:00 EDT
E.I. Guerrero-Cruz, O.A. Rodríguez-López, M.A. Solís
For a weakly interacting Bose gas trapped by an imperfect one-dimensional artificial crystal, we study the effect of its punctual defects, i.e. vacancies, on the ground state properties of the system. In the framework of the mean field approximation, we numerically solve the corresponding Gross-Pitaevskii equation using the ``Gradient Flow with Discrete Normalization’’ method, also known as the imaginary time method. The crystal is artificially produced by applying an external Dirac comb potential to the Bose gas where vacancies are created by randomly removing a predetermined number of deltas. We observe that as the number of randomly removed deltas increases, the ground state energy decreases exponentially from its value for the perfect crystal case until it reaches its value when the Bose gas is free.
The ground state energy is reported for different magnitudes of the interaction between bosons and several system sizes which we extrapolate to infinity for the crystal with only one vacancy. Also, we observe the presence of an energy gap between the ground state energies of the perfect system and that with a vacancy, which is more noticeable for values of the particle interaction magnitude $ g \leq 0.1$ , when the delta strength $ P_0 = 10$ . In addition, we report the boson distributions within the crystal,
%inside a box with periodic boundary conditions,
i.e. the probability density functions which show
localization features around vacancies which disappear as $ g$ increases. From the ground state energy, the chemical potential is obtained immediately.
Quantum Gases (cond-mat.quant-gas), Materials Science (cond-mat.mtrl-sci)
8 pages, 8 figures
Magnetic devil’s staircase in UAgBi$_{2}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
G. S. Freitas, K. Kirchner, C. Girod, D. R. Yahne, W. Simeth, C. S. T. Kengle, F. B. Carneiro, P. G. Pagliuso, J.D. Thompson, M. Janoschek, O. Zaharko, S.M. Thomas, P. F. S. Rosa
Materials characterized by competing interactions often exhibit a large number of nearly degenerate periodic states. Here we show that layered UAgBi$ _2$ hosts a cascade of field- and temperature-induced magnetic transitions. Based on specific heat, thermal expansion, and neutron diffraction, we construct a phase diagram that reveals at least seven nearly degenerate magnetic states in UAgBi$ _2$ . The observed multi-step magnetization process can be understood by square-wave structures with distinct propagation vectors $ \mathbf{k}$ =(0, 0, \textit{k}) in the presence of strong easy-axis anisotropy that confines the moments along the \textit{c} axis. Our findings are consistent with a magnetic devil’s staircase described by the axial next-nearest neighbor Ising (ANNNI) model and place UAgBi$ _2$ as a rare realization of the devil’s staircase in a 5\textit{f}-electron system.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
A new perspective on the anomalous Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Jason G. Kattan, Matthew Albert, J. E. Sipe
We revisit the anomalous Hall effect in magnetic conductors, and its generalization to finite frequencies, using a formalism based on microscopic notions of polarization, magnetization, and free charges and currents. The electronic degrees of freedom are treated within second-quantized field theory, where the Hamiltonian features a static and cell-periodic magnetic field that encodes the magnetic order in the crystal and breaks time-reversal symmetry. We study the dynamics of bound and free charge carriers at the microscopic level as they respond to a spatially uniform electric field at finite frequency. The conductivity tensor describing the long-wavelength response is a sum of three terms, including a Kubo term associated with the polarization response, along with the metallic Drude term and the anomalous Hall conductivity that are associated with the longitudinal and transverse parts of the free current response, respectively. We also present numerical calculations of these contributions for the ferromagnetic body-centered cubic phase of iron.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Negligible current-induced torque from the bulk and interface of Al
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Taiyang Zhang, Lujun Zhu, Zhihao Yan, Lijun Zhu
The light metal Al was predicted to have strong orbital Hall and Rashba effects from its bulk and interface, respectively. In this letter, we report experimental evidence that neither the bulk nor the interface of the Al contributed a detectable torque on adjacent Co and FePt layers with significant spin Hall effect, spin-orbit coupling, and resistivity mismatch with Al. These results suggest minimal orbital-spin conversion in Al and negligible orbital transport and spin-vorticity torque in Co/Al, Al/Co, and Al/FePt bilayers. Our findings suggest poor generality and/or effectiveness of torque contributions by the orbital Hall effect, the interfacial orbital Rashba effect, and the spin-vorticity coupling.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Superheavy dark-bright soliton as a signature of spatial symmetry breaking transition in harmonically trapped Bose mixtures
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-07-13 20:00 EDT
Zheng Gao, Ling-Zheng Meng, Jie Liu, Li-Chen Zhao
We investigate the dynamics of a dark-bright soliton in harmonically trapped two-component Bose-Einstein condensates and reveal an interesting spontaneous spatial symmetry breaking driven by nonlinear interactions. When the interaction parameter crosses a threshold value, we find that the dark-bright soliton’s motion demonstrates a transition from symmetric periodic oscillation about the origin to asymmetric oscillations offset from the origin. In particular, at the transition point, the effective soliton mass, determined by the ratio of inertial mass to physical mass, diverges. The underlying mechanism is uncovered by constructing trial wave functions and employing the Lagrangian variational method to obtain an effective potential in the quasiparticle picture, which changes from a single well to a double well. The anomalous ``superheavy soliton’’ phenomenon is a direct consequence of the dark-bright soliton’s physical mass vanishing at the transition point. We obtain the phase diagram of this spatial symmetry-breaking transition. Possible implications of our finding for quantum metrology are discussed.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS)
10 pages, 2 figures
Predictive Renormalization-Group Theory of Universality Classes in Nonlinear Systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
Universal scaling behavior appears across a wide range of nonlinear systems despite substantial differences in their governing equations and physical mechanisms. We develop a renormalization-group (RG) framework that identifies two complementary RG mechanisms underlying such universality. First, scale invariance generates RG fixed points corresponding to asymptotic self-similar solutions. Second, repeated RG transformations eliminate non-scale-invariant irrelevant structures, causing broad classes of equations to flow toward the same fixed points and thereby form universality classes. The framework applies to finite-time singularities, long-time intermediate asymptotics, stochastic Edwards–Wilkinson growth, nonlinear diffusion, density-dependent biological diffusion, and fluid-interface dynamics. In each case, it reproduces known scaling behavior and identifies the associated universality class through explicit irrelevance criteria. A central feature of the framework is its predictive character. Once a scale-invariant fixed point is identified, the theory predicts entire families of nonlinear equations sharing the same asymptotic self-similar solution. While the diffusion class is partially supported by existing mathematical RG results, most universality classes identified here have not previously been established and therefore constitute falsifiable predictions. These results provide a unified RG perspective on universality in nonlinear systems and show that universality emerges from the same fundamental RG principles that underlie critical phenomena. In contrast to critical phenomena, where observable behavior is typically governed by unstable fixed points requiring fine tuning, self-similar dynamics are generally selected through dynamically stable RG fixed points.
Statistical Mechanics (cond-mat.stat-mech)
14 pages, 3 figures
Quantum Hopfion rings in the cluster mean-field approximation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Vladyslav M. Kuchkin, Thomas L. Schmidt
We study the quantum properties of two- and three-dimensional spin textures – $ k\pi$ -skyrmions and hopfion rings – within the cluster mean-field approximation (CMFA). By combining the CMFA with a symmetrization procedure, we achieve two key advances: the accurate computation of quantum fluctuations in large spin textures and reliable access to metastable states. These challenges are generally insurmountable using standard methods, which are severely limited by the curse of dimensionality and typically restricted to ground-state properties. Exploiting the cylindrical symmetry of the studied magnetic configurations, we construct one-dimensional chain-like clusters that can be efficiently simulated using the density matrix renormalization group method, while inter-cluster interactions are treated at the mean-field level. The resulting spatial profiles of quantum features such as the local variation of the magnetization length in hopfion rings reveal limitations of the classical micromagnetic model and indicate the necessity of its extension. We demonstrate that the recently proposed regularized micromagnetic equation provides a suitable framework for this purpose.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 4 figures
Shear Unfreezing Explains Yielding, Plasticity and Neck Initiation of Glassy Polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-13 20:00 EDT
Peihan Lyu, Zhaoyu Ding, Masao Doi, Xingkun Man
Yielding, plasticity, and necking are central to the mechanical performance of materials, yet a concise unified physical picture of how these nonlinear responses arise remains lacking. We develop a minimal theory for glassy polymers based on a classical volume-dependent relaxation time following the Doolittle equation, and derive the constitutive relation using the Onsager variational principle. Surprisingly, this simple theory explains yielding, plasticity, and neck initiation under constant strain rate loading via a shear unfreezing mechanism: as the sample is stretched, volume-increasing activated molecular mobility drives shear deformation from an initially frozen state to an unfrozen state. The theory yields an analytical expression for the yielding stress as a function of strain rate and temperature. It also predicts a phase diagram for necking initiation in the same parameter space, providing a mechanism beyond the classical Considère criterion. Our results establish a unified framework for nonlinear tensile behavior in glassy materials.
Soft Condensed Matter (cond-mat.soft)
6pages, 4 figures
Tunable responsivity and bandwidth in microwave kinetic inductance detectors via readout current nonlinearity
New Submission | Superconductivity (cond-mat.supr-con) | 2026-07-13 20:00 EDT
Maclean Rouble, Peter Day, Matt Dobbs, Joshua Montgomery, Sofiia Savchyn, Graeme Smecher
Microwave kinetic inductance detectors (MKIDs) are generally read out with microwave readout tones of high enough amplitude to adequately suppress the noise contribution of the first-stage amplifier. At high readout power, the detector’s resonant frequency is altered as a result of the dependence of the kinetic inductance on the internally circulating microwave current. With the tone placed below the resonant frequency, the nonlinear frequency shift results in a positive feedback effect that can significantly enhance the responsivity of the detector, to both optical and microwave power. We report a factor of 10 enhancement in optical response by tuning the readout power and frequency to close to the resonator’s bifurcation point. A corresponding decrease in the bandwidth of the resonator is observed under these conditions. We show that the strength of the feedback effect can be easily selected by adjusting the excitation, and provide a map of possible operational states to do so. Operation of MKIDs in this mode could be used to improve sensitivity when non-intrinsic noise sources are significant.
Superconductivity (cond-mat.supr-con), Instrumentation and Methods for Astrophysics (astro-ph.IM)
11 pages, 8 figures
Topological phase transition driven by Hatsugai-Kohmoto interaction on the Kagome lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
The interplay between band topology and strong correlations is central to modern condensed matter physics, but exact solutions are rare. Here, we present an exactly solvable model on the Kagome lattice by combining a Kane-Mele-type spin-orbit coupling with the Hatsugai-Kohmoto interaction. At 1/3 filling, we uncover a continuous topological quantum phase transition driven by electron interaction. A weakly correlated $ \mathbb{Z}_2$ topological insulator gives way to a strongly correlated insulator that, while $ \mathbb{Z}_2$ -trivial, hosts a nontrivial spin Chern number $ C_s=2$ . The transition exhibits critical scaling consistent with the universality class of two-dimensional Dirac fermions. At half-filling, the same model yields a non-Fermi-liquid to Mott-insulator transition, demonstrating that correlation-driven topological and Mott transitions can be unified within a single solvable framework. Our results establish the Kagome Hatsugai-Kohmoto model as a valuable benchmark for interacting topological systems.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 4 figures
Screening-controlled dynamical criticality in the quantum Hall regime
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Tanima Chanda, Simrandeep Kaur, Anantbir Virk, Kenji Watanabe, Takashi Taniguchi, G. J. Sreejith, Yuval Gefen, Aveek Bid
At continuous electronic phase transitions, Coulomb interactions can modify the relation between length, energy, and temperature, but experimentally disentangling their effects on spatial versus dynamical criticality has remained difficult, since finite-temperature scaling alone measures only the combined exponent $ \kappa = 1/(z\gamma)$ . Here, we introduce two advances that resolve this limitation. First, by combining temperature scaling with independent current scaling, we separately extract the dynamical exponent $ z$ and the localization-length exponent $ \gamma$ at the quantum Hall plateau transition – rather than inferring one from an assumed value of the other. Second, using dual-graphite-gated graphene devices in which the effective Coulomb interaction range is tuned geometrically by the ratio of the magnetic length $ l_B$ to the graphite-gate distance $ d$ , we track this separation across both screened and unscreened interaction regimes within the same device platform. Temperature scaling gives $ \kappa \simeq 0.21$ in the screened regime and $ \kappa \simeq 0.41$ in the unscreened regime; combining this with current scaling reveals that screening changes $ z$ from $ \simeq 1$ in the unscreened regime to $ \simeq 2$ in the screened regime. In contrast, $ \gamma$ remains close to $ 2.4$ throughout. Our results establish that gate-controlled screening selectively modifies the interaction-dependent dynamical sector of the quantum Hall transition, leaving the localization-length exponent $ \gamma$ unchanged within experimental uncertainty. More broadly, this work establishes geometric screening as a versatile tool for controlling interactions and disentangling interaction and disorder effects in correlated two-dimensional systems, including fractional quantum Hall states, moiré materials, and other strongly localized electronic phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
22 pages
Observation of a Rydberg-atom time crystal with an ultralong lifetime
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-07-13 20:00 EDT
Qi-Feng Wang, Tian-Yu Han, Ya-Jun Wang, Dong-Yang Zhu, Chao Yu, Yu Ma, Yi-Ming Yin, Guang-Can Guo, Bang Liu, Li-Hua Zhang, Dong-Sheng Ding, Bao-Sen Shi
Continuous time crystals (CTCs) represent a nonequilibrium quantum phase that spontaneously breaks time-translation symmetry without periodic external driving, manifesting as persistent, long-lived oscillations under steady pumping. The lifetime is constrained by the instability of the limit cycle phase, balanced between nonlinear feedback and energy dissipation, which have rarely been studied in experiments before. Here, we report an observation of an ultralong-lived Rydberg-atom CTC in a driven-dissipative many-body atomic system. By harnessing long-range interactions and engineering a dissipative environment that stabilizes the limit-cycle dynamics, we suppress heating and decay effects that typically destroy time-crystalline order. The key factor underlying the ultralong-lived CTC is the closing of the Liouvillian gap and the near-zero real part of the system’s Liouvillian eigenspectrum. Through systematic optimization, we achieve an oscillatory lifetime exceeding 16.95 hours-orders of magnitude longer than previous CTC realizations. Our work establishes a robust platform for exploring long-lived autonomous nonequilibrium phases and paves the way for applications in quantum sensing and continuous-time quantum information processing.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
Terahertz field-driven nonlinear Hall effect and other second order transport phenomena in two-dimensional tellurene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
M. D. Moldavskaya, L. E. Golub, E. Mönch, Chang Niu, Peide D. Ye, J. Wunderlich, S. D. Ganichev
We study terahertz field-driven second-order nonlinear electron transport phenomena, including the nonlinear Hall effect (NLHE), in two-dimensional tellurene flakes. The dc current excited by linearly polarized terahertz (THz) radiation in Hall bar samples is investigated in directions both along and perpendicular to the $ c$ -axis of tellurene. As expected for second-order transport phenomena, the current scales as the square of the in-plane electric field of the radiation $ \bf E$ , and depends on its orientation. The current results from a combination of three contributions, including the NLHE, the Nonlinear Longitudinal (NLL) and Nonlinear Diagonal (NLD) currents. We established the equivalence between NLH, NLL, and NLD transport currents and Linear photogalvanic effect (LPGE) contributions induced by the absorption of linearly polarized and unpolarized THz radiation. All contributions can be controlled by a gate voltage and have opposite signs for electron and hole conductivity. The magnitude of the current increases drastically when the samples are cooled from room temperature to 4.2 K. It also increases with decreasing radiation frequency. These results are well described by the developed phenomenological and microscopic theories. We show that the THz radiation-induced electric current originates from microscopic mechanisms such as skew scattering, side jump, and the Berry curvature dipole.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
13 pages, 9 figures
The scales of disorder in perfect quasicrystals
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
Alan Rodrigo Mendoza Sosa, Atahualpa S. Kraemer, Michael Schmiedeberg, Erdal C. Oğuz
The classical dichotomy between crystalline order and amorphous disorder is increasingly challenged by novel states that lack conventional crystalline symmetries while retaining crystal-like properties. Quasicrystals occupy a distinctive position within this expanding framework by possessing long-range order without translational periodicity, thereby permitting arbitrary $ N$ -fold rotational symmetry. Paradoxically, far from their unique symmetry center, high-symmetry quasicrystals closely resemble disordered patterns, raising the question of how deterministic order can be detected. Here we show that increasing rotational symmetry progressively suppresses local statistical signatures of quasiperiodicity, while preserving its underlying exact long-range order. This order is thus concealed below an emergent crossover length that grows linearly with $ N$ . Therefore, as $ N \rightarrow \infty$ , the disorder-like regime expands without bound, defining a symmetry-controlled geometric critical point at which deterministic order and randomness become statistically indistinguishable over any finite observation window. For finite $ N$ , however, quasiperiodic order becomes detectable beyond this crossover, revealing a second emergent length scale that we identify as the size of a \textit{statistical unit cell} – finite patches over which statistical properties recur despite the absence of conventional translational periodicity. In one dimension, the statistical-unit-cell size coincides with the crossover length, whereas in two dimensions it grows as $ N^2$ , remaining smaller than the size of typical approximants and establishing a hierarchy of emergent length scales. Together, the disorder-to-order crossover and statistical unit cells provide a quantitative framework connecting crystals, quasicrystals, and amorphous matter, showing how apparent disorder can emerge from purely deterministic geometry.
Statistical Mechanics (cond-mat.stat-mech)
22 pages, 13 figures
Transient Reserves, Sink Dampers, and the Failure of Eigenvalue Reasoning in the Attention Propagator
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-07-13 20:00 EDT
Li Hengyu (Institute for Solid State Physics, The University of Tokyo)
The attention matrix of a causal transformer is row-stochastic, iterated over depth, and non-normal by construction. For non-normal operators, eigenvalues control only asymptotic behavior; finite-depth behavior is controlled by resolvent quantities such as pseudospectra and Kreiss constants. We test, under pre-registered criteria, whether this resolvent view predicts anything about trained transformers that eigenvalues miss. Two structural facts organize the analysis: the mask pins the Kreiss constant of every causal stochastic matrix at $ \sqrt{n}$ , and deflating the mask-forced Perron projector factorizes the depth deviation dynamics exactly into a product of deflated operators. Across GPT-2, Pythia-410m, and Llama-3-8B, learned non-normality proves to be signed. A routing minority carries excess transient reserve that tracks previous-token function and doubles when induction heads engage, while the sink majority is suppressed below matched shuffle nulls, so that attention sinks act as transient dampers. On depth products, eigenvalue predictions of surviving deviations err by seven to eleven orders of magnitude, an error absent in matched nulls. Checkpoint censuses date this organization to a consolidation phase after circuit formation, and a clamping intervention on Llama-3-8B establishes a causal chain from three massive activation dimensions through sink attention to transient damping; LayerNorm models implement the same functions elsewhere. A cross-validated contest concludes that resolvent features are required for depth-transient persistence and routing-head identity, and that no single-operator summary of any kind predicts per-head causal criticality.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
17 pages, 8 figures. Companion paper: arXiv:2607.06621
Kinetic Cellular Model of Corrosion
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Aqueous corrosion of metals involves multiple interconnected processes. Thus, computer simulation of corrosion as a whole needs to be able to describe the individual processes and how they influence each other. Atomistic simulations are designed to obtain detailed information for small regions of space over short times. Thus there are limits to the understanding that can be obtained by atomistic simulations alone. Here is presented a method that uses generalised rate equations to extend the length and time scales that can be accessed. It is shown to reduce to either the phase field or cellular automata methods in certain limits. The generalised kinetic equations can reproduce the behaviour described by both the Nernst-Planck and Butler-Volmer equations, which are frequently used to describe corrosion. In addition, the method can describe local rearrangements of atoms such as chemical reactions. Example results are shown for illustrative 1D and 2D problems, with good agreement being found with other methods.
Materials Science (cond-mat.mtrl-sci)
27 pages, 6 figures
Learning to Converge: Warm-Starting DFTB Self-Consistent Charges with Machine Learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Maximilian L. Ach, Karsten Reuter, Chiara Panosetti
Semiempirical electronic structure methods such as Density-Functional Tight-Binding (DFTB) offer a computationally efficient approach to molecular and materials simulations, bridging the gap between first-principles accuracy and classical force field speed while retaining full access to electronic properties. However, DFTB calculations based on self-consistent charge (SCC) schemes can still suffer from slow convergence, particularly for complex molecular and materials systems, making the iterative procedure a significant bottleneck in large-scale simulations and high-throughput workflows. We present a machine learning approach that accelerates DFTB simulations by predicting optimal initial atomic charges. Using element-specific models based on the Smooth Overlap of Atomic Positions descriptor and kernel ridge regression, we train charge models on reference calculations and demonstrate that ML-predicted initial charges consistently and significantly improve SCC convergence across diverse chemical systems including organic molecules, biomolecules, water clusters, transition metal oxides and solid electrolytes.
Materials Science (cond-mat.mtrl-sci)
10 pages, 2 figures
Semi-Empirical Kinetic Model for Phase Selection in Rapidly Solidified Multicomponent Concentrated Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
O.I. Kushnerov, S.I. Ryabtsev, V.F. Bashev
A semi-empirical kinetic framework is formulated for predicting phase selection in multicomponent concentrated alloys under rapid solidification. The approach is based on the critical cooling rate required to suppress competing crystalline pathways and combines topology-dependent ranking of BCC-, FCC-, and HCP-like crystallization pathways with a correction for glass-forming ability. The formulation includes a topology-dependent viscosity correction with a smoothed BCC multiplier and a continuous correction factor for glass-forming ability based on mixing enthalpy, excess entropy, and atomic-size dispersion. Comparison with experimental and computational data shows that the kinetic criterion captures changes in the lattice type expected from the valence electron concentration criterion, describes kinetic suppression of phase separation, and identifies competitive multiphase crystallization. The model also distinguishes alloys with high and low glass-forming ability. The proposed framework provides a practical approach for preliminary evaluation of kinetic phase competition in rapidly solidified multicomponent melts.
Materials Science (cond-mat.mtrl-sci)
11 pages, preprint version
Is the Eyring Plot Misleading? A Case for Arrhenius Analysis of Activation Parameters
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
A common view in physical chemistry literature is that the Eyring representation, in which a linear fit of $ \ln(k/T)$ versus $ 1/T$ is attempted, is more fundamental than the Arrhenius representation, $ \ln(k)$ versus $ 1/T$ . This perception is typically motivated by its derivation from statistical mechanics and quantum mechanics, and by the interpretation of the intercept in terms of the activation entropy $ \Delta S^\ddagger$ , whereas the Arrhenius equation and its prefactor are often regarded as purely phenomenological. However, harmonic approximation models yield exact linearity in Arrhenius plots but not in Eyring plots, although for real experimental data both generally appear equally linear within typical experimental accuracy. Furthermore, the impression that the Eyring formulation is inherently quantum mechanical arises from the presence of the Planck constant in the prefactor, whereas this term results from normalization conventions in the partition function. This also highlights an interpretational issue in $ \Delta G^\ddagger$ , which is based on partition functions of different dimensionality between reactant and transition state. This dimensional mismatch can be reformulated in an alternative representation that improves interpretability and reduces to an Arrhenius-type expression in which the prefactor is directly related to an entropy of activation. In this framework, both activation enthalpy and entropy obtained from an Arrhenius fit are arguably more physically relevant than the corresponding Eyring fit values.
Statistical Mechanics (cond-mat.stat-mech)
Quantifying nanoparticle size effect on the photoacoustic generation efficiency
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-13 20:00 EDT
Arthur Billon (LIB, NABI (UMR 8175 / U1334)), Sarah Boumati (LIB, IGPS), Lorenzo Mancini (IGPS), Charaf Eddine Benaddi (PPSM), Elise Michel (PPSM), Clément Linger (LIB, IGPS), Colin Schotté (LIB), Rachel Méallet (ISMO), Frédéric Gobeaux (LIONS), Gilles Clavier (PPSM), Nicolas Tsapis (IGPS), Jérôme Gateau (LIB)
Photoacoustic (PA) signal generation in colloidal suspensions of optically absorbing nanoparticles is dominated by the thermal expansion of water for gold nanoparticles, but remains mostly unexplored for organic nanoparticles. Here, we derive a model where the PA generation efficiency scales with particle size and thermoelastic contrast with water. The model is validated using solid lipid nanoparticles labeled with several BODIPY dyes. This experimental validation paves the way for quantitative PA characterization of nanomaterials and rational design of PA contrast agents.
Soft Condensed Matter (cond-mat.soft), Optics (physics.optics)
Dispersion Polymerization in an Elastomeric Solvent
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-13 20:00 EDT
Senthilkumar Duraivel, Reagan J Dreiling, Tyler E Ball, Harsha Koganti, Jay Fu, Ethan E. O’Banion, Brett P. Fors, Eric R. Dufresne
Polymerization-induced phase separation (PIPS) provides a powerful route to generate structured polymeric materials by coupling chemical conversion with thermodynamic demixing. PIPS in liquid-state systems underlies dispersion polymerization, serving as a cornerstone technique for microparticle production, yet is constrained by solvent compatibility and limited range of morphologies. Here, we establish an elastically mediated PIPS regime that bridges these two limits by conducting controlled polymerization within a deformable elastomeric network. This approach, termed Dispersion Polymerization in an Elastomeric Solvent (DiPolES), serves as a solid-state analogue of dispersion polymerization in which an elastomeric network simultaneously serves as solvent and physical stabilizer. Using photoiniferter-mediated polymerization of methyl methacrylate (MMA) within poly(dimethyl siloxane) (PDMS) elastomeric solvent, DiPolES enables robust fabrication of elastomeric composites containing uniform PMMA microparticles with tunable size (0.85 to 3 {\mu}m) and shape (spheroidal and ellipsoidal). The strategy is generalizable beyond the PDMS/MMA system and is applicable to diverse monomers, such as acrylonitrile and 2-vinyl pyridine, which can be extracted from the elastomeric solvent, enabling high-yield production of microparticles. Real-time imaging and compositional analysis reveal that particle formation proceeds through rapid nucleation at low monomer conversion, followed by growth accompanied by cavitation of the surrounding network. Monomer loading governs the particle size, while solvent elasticity modulates the transition from isolated uniform spheroids to heterogeneous clusters. Interestingly, applying uniaxial strain during DiPolES enables production of ellipsoidal particles without any post-processing.
Soft Condensed Matter (cond-mat.soft)
26 pages, 5 figures
Sixteenfold Classification of Many-Body Multipoles from Rotation-Compatible Canonical Symmetries
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
Shingo Kuniyoshi, Rikuto Oiwa, Satoru Hayami
The conventional multipole framework provides a standard symmetry-based language for one-body electronic degrees of freedom, but fails to distinguish physically distinct sectors in many-body operator space. We show that canonical symmetries compatible with rotations provide this structure through two additional 2 labels associated with the particle-number gauge transformation G{\pi}/2 and the particle-hole transformation CA. These labels separate operators with different body numbers and particle-number changes, leading to a sixteenfold classification that organizes selection rules for nonzero expectation values, induced multipoles, and symmetry-allowed couplings in many-body multipole space.
Strongly Correlated Electrons (cond-mat.str-el)
Finite-time cooling and accessibility of the stripe phase in the Ising antiferromagnet
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
The finite-rate cooling dynamics of the triangular-lattice $ J_1-J_2$ Ising antiferromagnet is studied under local Metropolis updates. Although an antiferromagnetic next-nearest-neighbor coupling selects a stripe phase in equilibrium, the simulations show that this phase is not automatically reached on finite time scales. A kinetic stripe-formation time $ n^\ast(L,J_2/J_1)$ is defined from the probability of obtaining a globally stripe-ordered final state. This time shifts to much slower cooling as the system size increases and to faster cooling as $ J_2/J_1$ increases. The size dependence is compatible with a coarsening-controlled process, with an effective growth at least quadratic in L over the simulated range. Real-space morphology and fixed-temperature diagnostics show that failed trajectories are not simply disordered states: they often contain locally stripe-ordered domains separated by residual walls or competing orientations. In the weak-$ J_2/J_1$ regime, the system can restore the local nearest-neighbor frustrated constraint while still failing to select a global stripe sector. These results separate three processes that are usually conflated: energetic degeneracy lifting by $ J_2/J_1$ , local constraint restoration, and global stripe-orientation selection under local dynamics.
Statistical Mechanics (cond-mat.stat-mech)
22 pages, 9 figures, 2 appendices. Uses RevTex 4-2. The code will be added on github
Unlocking ultrafast spin dynamics in a rare-earth magnet
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Paul Herrgen, Christian Holzmann, Torben Manzke, Ulrich Nowak, Peter M. Oppeneer, Manfred Albrecht, Benjamin Stadtmüller, Martin Aeschlimann
The speed of optically driven magnetization dynamics is fundamentally determined by how efficiently angular momentum can be transferred between electronic, spin and lattice degrees of freedom. In rare-earth magnets, this process is typically slow because optical excitation primarily addresses itinerant electrons, whereas the magnetic moment resides in localized 4f states. Here we show that selective optical excitation of localized magnetic states can overcome this limitation. Using femtosecond pump-probe magneto-optical spectroscopy of ferrimagnetic gadolinium iron garnet, we resonantly excite an intra-4f transition of Gd3+ at 4.65 eV and resolve the ensuing dynamics of the antiferromagnetically coupled Gd and Fe sublattices. Direct excitation of the 4f manifold induces an ultrafast demagnetization of the Gd sublattice with a characteristic time of 38 fs, more than two orders of magnitude faster than in elemental gadolinium and even faster than the response of the Fe sublattice in the same material. By contrast, off-resonant excitation strongly suppresses the acceleration of the Gd dynamics while leaving the Fe response largely unchanged. These results demonstrate that the ultrafast magnetic response of rare-earth systems is governed not only by intrinsic material properties but also by the optical excitation pathway. Selective access to localized magnetic states therefore provides a powerful photonic handle for engineering angular-momentum flow and controlling magnetism far from equilibrium.
Materials Science (cond-mat.mtrl-sci)
The Statistical physics of unsaturated soil water: kinetic theory and non commutative pore water dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
We develop a statistical-mechanical theory of water in unsaturated soil whose outcome is a continuum field equation for the pore-occupancy g(r,x,t), the fraction of pores of radius r that are water-filled at position x and time t. The theory is built across three scales: microscopic inter-pore transfers set by Hagen-Poiseuille rates and a driving potential (the difference of pore-class chemical potentials, taken in capillary-gravitational form but open to adsorptive, osmotic, or thermal refinement); a mesoscale master equation relaxing the occupancy toward the equilibrium step g_eq=H(r\ast-r); and, on contracting the averaging volume to a point, the continuum balance d_t g + div F = C[g] - E - T, of which everything else is a limit, a moment, or a boundary resolution. The kinetic equation is an Onsager gradient flow descending the Gibbs free energy, with an H-theorem for the isothermal unforced system and mass conservation as its zeroth moment. A single dimensionless group, the pore-resolved Damkohler number Da(r,x), organizes the behavior and unifies phenomenologies long modelled separately. A Chapman-Enskog reduction identifies Richards’ equation as the quasi-static (Da->0) limit, with matric potential and hydraulic conductivity K emerging only there and K vanishing below the percolation threshold; capillary-bundle and critical-path models are its diagonal and spectral limits. Hysteresis is the holonomy of a forcing bundle, a geometric phase rather than per-pore bistability, with a falsifiable loop-area law H ~ I^2. Preferential flow is what the same equation does where Da>1, so the Richards/preferential-flow dichotomy becomes a continuous Da-controlled crossover. Out of the quasi-static limit g(r) is the irreducible state variable. All inputs are geometric properties of the pore network, measurable from micro-CT and calibrated against no macroscopic data.
Statistical Mechanics (cond-mat.stat-mech), Geophysics (physics.geo-ph)
Main paper plus supplemental material
Coherent dynamics of individual excitons in a quantum dot embedded in a nanopost
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Maxime Gaignard, Karolina Ewa Polczynska, Niels Gregersen, Daniel Wigger, Jean-Philippe Poizat, Jean-Michel Gérard, Julien Claudon, Jacek Kasprzak
We measured coherent ultrafast dynamics of exciton complexes in a single strongly-confined InAs quantum dot embedded in a GaAs nanopost. Such a photonic structure combines a wave guiding with a cavity effect and assures an enhanced light-matter coupling. Coherence properties of an exciton-biexciton system hosted by a quantum dot are assessed with four-wave mixing microscopy. Our results show that this broad-band photonic structure is an excellent asset to probe coherent couplings in a small set of solid state quantum systems and to investigate the coherence dynamics within the level structure of their excited states.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Short-range magnetic order and multi-stage phase transitions in the easy-plane van der Waals magnet CrCl$_3$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
T. B. Mazitov, M. I. Panin, A. S. Pakhomov, M. V. Bakhmetiev, E. O. Chiglintsev, A. I. Chernov, A. A. Katanin
We investigate the evolution of spin correlations and the nature of the multi-stage magnetic transition in the quasi-two-dimensional easy-plane van der Waals magnet $ \rm CrCl_3$ . By combining broadband ferromagnetic resonance (FMR) spectroscopy and DC SQUID magnetometry on mechanically exfoliated micro-flakes with non-local dynamical mean-field theory (DFT+DMFT) calculations, we analyze both long- and short range magnetic order in CrCl$ _3$ . Experimentally, SQUID and FMR measurements confirm the presence of the crossover to a spin polarized phase with the subsequent transition into an antiferromagnetic ground state upon cooling, but show robust short-range correlations at temperatures far above the magnetic ordering temperatures. Theoretically, we show the existence of highly stable local magnetic moments at room temperature, with a giant room temperature lifetime $ \tau$ of 130–300 ps due to a wide Mott bandgap. Below room temperature, a rapid growth of the in-plane correlation length $ \xi$ signals the formation of strong short range magnetic order consistent with the experimental observations. We also obtain a temperature-driven crossover of the interlayer exchange interaction, which changes from positive (ferromagnetic) at high temperatures to negative (antiferromagnetic) in the low-temperature ordered phase.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
10 pages, 12 figures
Electronic manipulation of polar order in electron crystal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Takashi Kikkawa, Ziyan Chen, Yuto Fujimoto, Takahiro Morimoto, Yuya Hirata, Hiroki Arisawa, Alexey A. Kaverzin, Satoshi Okamoto, Yoichi Okimoto, Naoshi Ikeda, Eiji Saitoh
When interaction among atoms or ions is strong enough, they often arrange periodically, forming a crystal. The arrangement patterns of atoms or ions can encode information, a concept that has enabled devices such as ferroelectric memories. It has been found that not only atoms or ions but also electrons in condensed matter can crystallize when Coulomb interaction is strong enough. Typical examples are charge-ordered states in solids, where different valences, or different electron numbers, of an ion spontaneously form a spatial pattern on the lattice. In such electron crystals, information is expected to be encoded into the electron-ordering patterns. Here, we demonstrate electronic manipulation and readout of charge-ordering directions in a paramagnetic semiconductor LuFe$ _2$ O$ _4$ . By applying current pulses at room temperature, we observed that the non-reciprocal resistivity of LuFe$ _2$ O$ _4$ is modulated along with a sign reversal, which disappears above the charge-ordering temperature. A numerical calculation incorporating inter-band Berry curvature affected by the charge ordering is consistent with the experimental results. By applying the observed phenomenon, we also demonstrate a non-reciprocal resistance memory operation in the charge-ordered LuFe$ _2$ O$ _4$ . This result opens the door to realizing charge-ordering electronics.
Materials Science (cond-mat.mtrl-sci)
39 pages, 7 figures
Effective theories for many-body systems with nonuniform symmetries
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
The low-energy dynamics of many-body systems is governed by gapless modes whose properties are dictated by symmetry. Their existence follows from Goldstone’s theorem, while their effective description at zero temperature is determined by the pattern of symmetry breaking. At finite temperature, an analogous role is played by hydrodynamics, which describes the universal behavior of many-body systems over long times and large distances. These principles are well understood for uniform symmetries, which act homogeneously in spacetime and lead to a correspondence between massless Goldstone modes and broken generators, as well as gapless hydrodynamic modes and conserved charges. However, this simple picture changes in the presence of nonuniform symmetries, whose generators do not commute with spacetime translations. The low-energy implications of these symmetries remain less understood, as they do not introduce additional gapless modes but instead constrain the dynamics of the existing degrees of freedom. In this thesis, we develop a unified framework for many-body systems with nonuniform symmetries and show that their effects can be understood in terms of additional fields that are not independent at low energies and can be eliminated, leading to kinematic constraints that reshape the infrared dynamics. In systems with spontaneous symmetry breaking, this mechanism modifies the effective theory and often softens the dispersion relations of the remaining modes. At finite temperature, it manifests in hydrodynamics as constraints on macroscopic currents. As a result, nonuniform symmetries give rise to qualitatively new physical phenomena, including modified spectra of collective excitations, exemplified by transverse Tkachenko oscillations in quantum vortex crystals, and unconventional transport phenomena, such as anomalously slow diffusion and softened sound modes in dipole-conserving systems.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), High Energy Physics - Theory (hep-th)
PhD thesis
Universal scaling of conformations of tangentially driven ring polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-13 20:00 EDT
Antonio Lamura, Marisol Ripoll
The interplay of tangential activity and excluded-volume interactions in ring polymers adsorbed to a surface, consistently results in the overall swelling of the ring configurations. This is in strong contrast to the case for three dimensional linear and ring polymers, where activity induces frequently collapsed structures. By means of Brownian Dynamic simulations, we investigate how the scaling properties of such active rings can be universally characterized by an activity-dependent Flory exponent, as a generalization of the equilibrium behavior. At high activity, an effective persistence length characterizes the conformations of active flexible rings.
Soft Condensed Matter (cond-mat.soft)
Under review
Anisotropic Superconductivity with Enhanced Critical Field in Strained RuO2
New Submission | Superconductivity (cond-mat.supr-con) | 2026-07-13 20:00 EDT
Younes Ghorbani, Samuel Poage, Xuehsi Gao, Luka Mitrovic, Neha Wadehra, Benjamin Gregory, Suchismita Sarker, Betul Pamuk, Andrej Singer, Darrell G. Schlom, Chun Ning Lau, Kaveh Ahadi
The superconductivity in RuO2 emerges under strain. RuO2 is also an altermagnet candidate. The nature of superconductivity and its relation with neighboring orders, however, are not understood. To address this problem, we grew epitaxial RuO2 films on TiO2(100) and TiO2(110) single crystal substrates and studied the electronic transport and emergent superconductivity along various crystallographic directions. We show that the superconducting transition strongly depends on the growth orientation and the crystallographic direction of the transport in the RuO2 films. We also observe a strong violation of Pauli paramagnetic limit with in-plane applied magnetic field which we attribute to strong spin-orbit scattering. These results offer opportunities for epitaxially engineered superconductors.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Level statistics in the fractal phase of generalized Rosenzweig–Porter models
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-07-13 20:00 EDT
Victor Delapalme, Leticia F. Cugliandolo, Alexander K. Hartmann, Marco Tarzia, Davide Venturelli
The Rosenzweig–Porter (RP) random matrix ensemble has emerged as a minimal model for the integrability-to-chaos crossover in quantum many-body systems. Its phase diagram features a region with fractal eigenstates, exhibiting intermediate spectral and localization properties between the fully localized and fully delocalized regimes. In this work, we explore several generalizations of the RP model and determine their level statistics at the scale of the Thouless energy $ E_T$ , which characterizes the crossover. Using tools from free probability theory and the replica method, we compute the full counting statistics in the limit of large system size, and show that it takes a simple, universal scaling form around $ E_T$ , shared across all variations of the model. We validate our analytical predictions using exact numerical diagonalization of large samples, and large-deviation algorithms that resolve the full counting statistics down to probabilities as low as $ 10^{-40}$ . We also contrast our predictions with measurements on the quantum random energy model, which is the simplest model displaying many-body localization.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
36+9 pages, 6+1 figures
Strongly correlated quantum matter: t–J model, real-space pairing, spin-dependent masses, and atomicity in chemical bond and nanosystems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
I critically overview my research on strongly correlated fermion systems for almost five decades. It concentrated on: (i) the first derivation of what is now called the t–J model, comprising both the limit of Anderson kinetic exchange of spin–spin interaction in the Mott–Hubbard insulator and taking into account real-space pairing, subsequently applied to high-temperature superconductivity; (ii) the concept of spin-dependent heavy mass of quasiparticles in heavy-fermion systems, and (iii) the first nontrivial model of statistical thermodynamics of the Mott–Hubbard transition. Those three features, together with the specific quantum critical phenomena provide, in my view, fundamental components of the theory of strongly correlated fermions established in the 1960s. Some related questions such as introduction of atomicity in the chemical bonding (iv), and specific properties of correlated nanosystems within the rigorous EDABI (v) approach are also briefly elaborated at the end.
Strongly Correlated Electrons (cond-mat.str-el)
J. Spa{\l}ek, Acta Phys. Pol. B 57, 5-A1 (2026)
Unraveling atomic-resolution valence electron energy-loss spectroscopic imaging in a single-crystal CaNb2O6
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-07-13 20:00 EDT
Sz-Chian Liou, Xiang-Lin Huang, Vladimir P. Oleshko, I-Ching Lin, Yin-Ping Lan, Hsin-An Chen, Guo-Jiun Shu
Despite advancements in electron optics and spectrometer design over the past twenty years, atomic-resolution valence-electron energy-loss spectroscopy imaging remains challenging due to the delocalization of inelastic electron scattering. In this study, we used an energy-filtered spectrometer equipped with a hybrid-pixel direct electron detector and spherical aberration-corrected scanning transmission electron microscopy to analyze many-electron excitations and interband transitions in a single-crystal calcium niobate, CaNb2O6, with spatial resolution ranging from the nanometers to the atomic scale. In the low-loss region above the bandgap at about 3.8 eV, we observed volume plasmons, around 6 eV and 15 eV energy loss, as well as a mix of strongly correlated plasmons and excitons, known as plexcitons, at approximately 7.3 eV energy loss. Additionally, we employed an on-axis EELS setup for atomic-resolution zero-loss peak (ZLP) imaging and visualized energy- and atom-resolved images of plexcitons and VPs, which showed contrast reversal relative to high-angle annular dark-field images. To investigate elastic contrast preservation, we also analyzed the effect of the collection angle and minimized its influence to produce delocalized VP images. In fact, the ZLP and VEELS images obtained using the weak-beam setup demonstrate that, in both cases, the contrast resembles Z-contrast. Moreover, we found that [NbO6] octahedra directly contributed to the lateral maps of interband transitions in the range from 3.2 eV to 3.5 eV energy loss. These findings demonstrate that Cs-STEM-EELS, which examines atomic-scale contrast associated with low-energy losses, can be a powerful tool for visualizing the structure, bonding, and electronic properties of complex crystalline nanostructures, including individual atomic sites, interstitial sites, and point defects.
Materials Science (cond-mat.mtrl-sci)
30 pages, 7 figures
Symmetry-Protected Pinch Curves in Classical Spin Liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
Classical spin liquids are correlated paramagnets in which local constraints generate extensive degeneracy and emergent gauge structures, often observable as pinch-point singularities in spin structure factors. Here we introduce pinch-curve spin liquids, in which the pinch singularities form one-dimensional algebraic curves in momentum space. Inversion symmetry protects these curves by reducing the singularity condition to two real algebraic constraints in three dimensions, and the geometry of the pinch locus is algebraically programmable. We identify elementary mechanisms for generating straight and curved pinch loci, construct lattice spin models that realize them, and test the predicted structure factors using Monte Carlo simulations. We further show that pinch curves can host an infrared Gauss-law transition: the leading local constraint and the associated anisotropic scaling of the structure factor change, even though the singular locus remains one-dimensional.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
6 pages, 5 figures, and supplemental material
Quantum Chaos with a Macroscopic Zero-Mode Sector
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
Cheryne Jonay, Kun W. Kim, Frank Pollmann, Alexander Altland
Chaotic many-body spectra are expected to densely fill their energy window. We show that constrained spin chains with chiral symmetry evade this expectation by hosting an exponentially large manifold of symmetry-protected exact zero modes separated from the surrounding spectrum by a sharp gap at zero energy. The gap is generated by chaotic level repulsion, with width set by the number of zero modes times the mean level spacing. We verify this mechanism in an East-West kinetically constrained chain, develop a minimal random-matrix description, and show how the gap can be detected through linear-response spectroscopy.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
5 pages, 3 figures
Majorana parity qubit in coupled minimal Kitaev chains
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Francesco Zatelli, Bart Roovers, Nick van Loo, Antonio Lombardi, Juan D. Torres Luna, Sebastian Miles, Vincent P.M. Sietses, Florian J. Bennebroek Evertsz’, Pablo Cova Fariña, Alberto Bordin, Ghada Badawy, Erik P.A.M. Bakkers, Michael Wimmer, Leo P. Kouwenhoven
Majorana zero modes provide a route to fault-tolerant qubits by encoding information non-locally in fermion parity. Their sensitivity to noise is expected to decrease exponentially with increasing separation between the Majoranas, a suppression known as topological protection. Kitaev chains engineered in quantum dot-superconductor arrays provide a tunable platform in which separated Majorana zero modes can emerge at the ends of the chain, even in two-site chains. These minimal-chain modes are known as poor man’s Majoranas and retain characteristic Majorana properties, including near-zero energy and equal electron-hole character, but have only limited protection. A key outstanding challenge is to move beyond identifying such modes in electrical transport measurements and achieve coherent qubit control in the time domain. Here, we demonstrate a Majorana parity qubit by realizing coherent coupling between two-site Kitaev chains. Since total fermion parity is conserved, the system separates into global even and odd parity manifolds. We observe coherent parity oscillations in both manifolds with equal oscillation frequencies at the Majorana sweet spot, as predicted for isolated Majorana zero modes. We further show that the oscillation frequency and coherence depend systematically on inter-chain coupling and quantum-dot detunings, in close agreement with our model for short, partially protected chains. Our results establish the first coherent control of a Majorana qubit, encoded in the fermion parity of Majorana zero modes in minimal Kitaev chains.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
A multi-ensemble mean-field reduction method for networks of globally coupled phase oscillators with arbitrary parameter distributions
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-07-13 20:00 EDT
Richard Gast, Shotaro Takasu, Helmut Schmidt, Ann Kennedy
Understanding the dynamical properties of coupled phase oscillator systems with heterogeneous oscillator frequencies has been a long-standing challenge of complex systems theory. While the seminal work of Ott and Antonsen dramatically improved our theoretical understanding of coupled phase oscillators for a small family of oscillator frequency distributions, we here present a mean-field reduction method for arbitrary frequency distributions. Our method leverages the drastic dimensionality reduction obtained for Lorentzian frequency distributions, and combines it with a data-driven multi-ensemble approach. As such, the method renders the Ott-Antonsen equations directly applicable to empirical distributions of phase oscillator frequencies, often achieving a drastic dimensionality reduction and allowing to study real-world physical and biological systems by means of stability, sensitivity, and bifurcation analyses.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Chaotic Dynamics (nlin.CD), Neurons and Cognition (q-bio.NC)
A nonstandard statistics for strongly correlated systems: Two simple examples
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
Józef Spałek, Piotr Kuterba, Mateusz Wójcik, Danuta Goc-Jagło, Maciej Fidrysiak, Leszek Spałek, Włodzimierz Wójcik
We discuss two different cases of strongly correlated fermions statistics. The first of them is the non-Fermi liquid (NFL) case, $ i.e.$ , that of fermions with exclusion of doubly occupancy of quasimomentum states $ {\bf k}$ with opposite spins ($ \uparrow\downarrow$ ). The second is that of statistical spin liquid (SSL) case, in which the fermion spins hop around and mix with the holes (unoccupied) states. For both cases we calculate the system entropy and the corresponding statistical distribution function, analyzed for a two-dimensional square-lattice filling $ n\in [0,1]$ and relative temperature $ k_B T/|t|$ , where $ t<0$ is the nearest neighbor hopping integral. We are particularly interested in the situation when the system of itinerant fermions reduce to the Mott-insulator state for the half-filled band ($ n\to1$ ). This limiting situation signals a qualitative difference between the present SSL statistics and that of uncorrelated fermions representing normal Fermi-liquid state.
Strongly Correlated Electrons (cond-mat.str-el)
Acta Phys. Pol. B 57, 5-A16 (2026)
A Boosted Energy Extraction from the CapMix Process by Grafting with Titratable Polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-13 20:00 EDT
Mamta Yadav, Clifford E. Woodward, Jan Forsman
Salinity gradient energy offers a sustainable route to convert ionic chemical potential differences into usable power. Capacitive mixing enables this conversion without membranes, but suffers from limited ion regulation at electrode interfaces. Here we show that by grafting electrode surfaces with titrating polymers, the performance can be substantially improved. Using Grand Canonical Monte Carlo simulations with exact image-charge Ewald summations, we demonstrate how the coupled effects of ion adsorption and charge regulation in response to an external potential can be harnessed. Grafted electrodes are shown to deliver substantially more energy relative to bare surfaces, driven by charge regulation effects that exploit the pH difference that typically exists between rivers and the ocean. While the effect is in principle maximized at high grafting densities and moderate chain lengths, the performance is fairly robust to variations of these parameters, within reasonable bounds. Complementary classical polymer Density Functional Theory calculations confirm these trends, validating the mechanistic framework. This work also establishes a practical approach to harvest electrical energy during wastewater neutralization, where acidic (or alkaline) effluents serve as complementary reservoirs, and offers a promising strategy to couple environmental remediation with renewable energy recovery.
Soft Condensed Matter (cond-mat.soft)
10 Figures
Delayed Arm Retraction Controls the Nonlinear Oscillatory Response of Long-Chain-Branched Polymer Melts
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-07-13 20:00 EDT
Dario Nichetti, Alessio Zaccone
Long-chain branching profoundly modifies the nonlinear oscillatory response of entangled polymer melts by introducing arm-retraction pathways absent in linear polymers. We present a molecular tube theory that explains the characteristic maximum of the Nonlinearity Index (NLI) observed experimentally in long-chain-branched polymers. The theory extends the recently developed nonlinear tube-orientation description of linear polymers by incorporating branch-point force transmission and delayed arm retraction. The backbone initially develops nonlinear orientation as in the corresponding linear polymer, whereas long-arm retraction subsequently relaxes the stored branch-point tension and progressively erases backbone orientational memory. This competition produces a characteristic NLI maximum followed by a post-peak decay. The theory predicts two distinct nonlinear regimes corresponding to sparse and dense long-chain branching and introduces an architecture parameter governing the height and width of the nonlinear peak. The resulting framework provides a molecular interpretation of nonlinear Fourier rheology and directly links the nonlinear harmonic response to polymer architecture.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Confinement drives valley splitting above 4K in buried silicon quantum wells
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
Davide Degli Esposti, Emma Catherine Brann, Asser Elsayed, Davide Costa, Mark Friesen, Giordano Scappucci
Controlling the energy scales of a quantum system is essential for defining robust qubits. In silicon spin qubits, the nearly degenerate conduction-band valleys create a leakage channel from the single-spin computational basis, posing a challenge to scaling and to shuttling-based architectures. Here, we measure the relevant energy scales of single-electron spin qubits in buried silicon quantum wells co-designed for low disorder and high valley splitting. Across a linear array of four quantum dots with an average orbital energy of 2.4(2) meV, we report an average single-electron valley splitting of 0.40(6) meV and an average two-electron singlet-triplet splitting of 0.24(7) meV. In three dots, we observe a strong correlation between valley splitting and orbital energy, with an average linear coefficient of $ \approx 0.22$ (meV/meV), demonstrating that electrostatic confinement can increase the valley splitting by several hundred microelectronvolts. In contrast, the remaining dot exhibits the highest valley splitting of 0.76(2) meV and low correlation, suggesting excellent characteristics for spin-qubit operation. Our findings demonstrate that strong confinement can be exploited in buried quantum wells to effectively enhance the valley splitting, thereby establishing a viable path toward the realization of shuttling and sparse-occupation-based architectures in low-disorder heterostructures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
10 pages, 4 figures
A Cloud-Accessible Open-Source Framework for the Electromagnetic Modelling of Applied Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2026-07-13 20:00 EDT
Yusen Guo, Alberto Paganini, Harold S. Ruiz
We present the H-cloud formalism, a cloud-accessible and open-source finite-element framework for electromagnetic modelling of applied superconductors. The proposed method expresses the nonlinear electromagnetic response of type-II superconductors in a curl-conforming discretisation based on Nédélec finite elements, where the tangential applied-field boundary condition, nonlinear E-J power law, and fully implicit time-discrete residual are stated explicitly at the variational level, all within a scripted Python finite-element workflow. The weak form is used as the basis for forward simulation and for extension to adjoint differentiation and PDE-constrained optimisation, while keeping the governing assumptions, boundary conditions, and solver structure fully visible to the user. The implementation is realised in Firedrake with UFL and PETSc-backed nonlinear solvers, allowing the identical script to run on local machines and in browser-accessible environments such as Google Colab without reformulating the problem. The method is verified on the canonical magnetisation benchmark of a cylindrical superconductor under Bean-like penetration conditions and then benchmarked against an independently constructed COMSOL model for a practical high temperature superconducting Bi2212 wire. Across matched mesh studies, the open-source workflow reproduces the commercial-reference magnetisation loops to within approximately (1%) , with relative peak errors below 1.5%, while cloud execution preserves the same numerical solution at rather modest additional runtime considering the use of (freely available) reduced hardware resources. The proposed framework provides a rigorous, reproducible, and portable route for superconducting simulation, benchmarking, and future optimisation-led modelling of applied and functional superconductors, shareable and executable into open cloud environments.
Superconductivity (cond-mat.supr-con), Mathematical Physics (math-ph)
12 pages, 2 figures. Supplementary material is available at this http URL
Thermalization in a Height-Conserving Quantum Dimer Model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-07-13 20:00 EDT
Junsheng Feng, Jie Ren, Zheng Yan
Strongly constrained quantum systems, in which local rules forbid most configurations, play a central role in condensed matter and lattice gauge theory. Their thermalization is often thought to be delicate: extensive conservation laws and dynamically frozen states can shatter the Hilbert space into many disconnected sectors. A natural question is whether, once the frozen states are removed, the dynamics within a single sector still thermalizes. We address this in the height-conserving quantum dimer model on the square lattice, whose local plaquette flips conserve an emergent height field. Resolving the winding numbers, the four sublattice heights, and lattice momentum , we isolate the dominant connected Krylov component of each fragmented sector and analyze its spectral spectral statistics, entanglement, and connectivity. The two standard chaos diagnostics then show different behavior:across momentum sectors the level-spacing statistics range from near-Poisoon to Wigner-Dyson, yet in every sector the eigenstate entanglement entropy collapses onto a narrow, dome-shaped curve characteristic of eigenstate thermalization. Only a handful of low-entanglement outliers interrupt this thermal pattern, in selected sectors. Thus, strong kinematic constraints can lead to a situation where spectral correlations and eigenstate thermalization need not follow the same universal signatures – a manifestation of constrained quantum chaos.
Strongly Correlated Electrons (cond-mat.str-el)
Fluctuation theorems for thermally isolated driven quantum systems: nonadiabaticity, excess work and strong inequalities
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-07-13 20:00 EDT
J. V. M. Steimetz, M. Campisi, M. V. S. Bonança
We expand on the ideas developed by C. Jarzynski in Physica A 552, 122077 (2020), where an integral fluctuation theorem was derived with the aim of obtaining thermodynamic inequalities stronger than those implied by the Jarzynski equality. Restricting ourselves to the quantum setting, we derive the corresponding detailed fluctuation theorem and additional detailed and integral fluctuation theorems; we also provide a clear physical interpretation of the stochastic quantities defined in the previous reference. Furthermore, we show that their averages are given by the nonadiabaticity parameter (i.e., the relative entropy between the final state after a finite-time driving protocol and the corresponding adiabatically evolved state) and the excess work (also known as inner friction). We elaborate on the inequalities derived from the fluctuation theorems and discuss their connection to irreversibility and formulations of the Second Law.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
19 pages, 6 figures
Silicon-Germanium Heterostructures with Enhanced Valley Splitting for Spin Qubits
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-07-13 20:00 EDT
David W. Kanaar, Efrain Martinez, Peihong Zhang, Mark F. Gyure
Achieving valley splittings well in excess of the thermal energy of electrons and avoiding valley excitations is essential for the consistent initialization, operation and readout of gate-defined Si spin qubits. In this work, we present a device-level optimization strategy for pushing valley splittings to between 1 and 5 meV, well beyond values reported in nearly all previous theoretical studies. Using device-scale simulations that incorporate atomistic alloy disorder through a 1D tight-binding theory, we demonstrate that our proposed approach yields large valley splittings with a tight distribution across disorder realizations, a key requirement for reproducible qubit performance at scale. The approach rests on an unorthodox Si/SiGe heterostructure design combining a narrow quantum well, a small Ge spike, and a pure-Ge cap. We corroborate these predictions with targeted atomistic density functional theory calculations. These results offer a clear path forward for scalable Si/SiGe spin qubit devices and, if realized experimentally, effectively eliminate valley splitting as an existential problem for large scale SiGe-based quantum processors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
9 pages, 10 figures