CMP Journal 2025-05-22
Statistics
Nature: 1
Nature Materials: 1
Nature Physics: 2
Nature Reviews Materials: 1
Physical Review Letters: 9
Physical Review X: 2
arXiv: 45
Nature
Signatures of chiral superconductivity in rhombohedral graphene
Original Paper | Electronic properties and devices | 2025-05-21 20:00 EDT
Tonghang Han, Zhengguang Lu, Zach Hadjri, Lihan Shi, Zhenghan Wu, Wei Xu, Yuxuan Yao, Armel A. Cotten, Omid Sharifi Sedeh, Henok Weldeyesus, Jixiang Yang, Junseok Seo, Shenyong Ye, Muyang Zhou, Haoyang Liu, Gang Shi, Zhenqi Hua, Kenji Watanabe, Takashi Taniguchi, Peng Xiong, Dominik M. Zumbühl, Liang Fu, Long Ju
Chiral superconductors are unconventional superconducting states that break time reversal symmetry spontaneously and typically feature Cooper pairing at non-zero angular momentum. Such states may host Majorana fermions and provide an important platform for topological physics research and fault-tolerant quantum computing1-7. Despite intensive search and prolonged studies of several candidate systems8-26, chiral superconductivity has remained elusive so far. Here we report the discovery of robust unconventional superconductivity in rhombohedral tetra- and penta-layer graphene without moiré superlattice effects. We observed two superconducting states in the gate-induced flat conduction bands with Tc up to 300 mK and charge density ne down to 2.4*1011 cm-2 in five devices. Spontaneous time-reversal-symmetry-breaking due to electron’s orbital motion is found, and several observations indicate the chiral nature of these superconducting states, including: 1. In the superconducting state, Rxx shows magnetic hysteresis in varying out-of-plane magnetic field B⊥–absent from all other superconductors; 2. the superconducting states are robust against in-plane magnetic field and are developed within a spin- and valley-polarized quarter-metal phase; 3. the normal states show anomalous Hall signals at zero magnetic field and magnetic hysteresis. We also observed a critical B⊥ of 1.4 Tesla, higher than any graphene superconductivity and indicates a strong-coupling superconductivity close to the BCS-BEC crossover27. Our observations establish a pure carbon material for the study of topological superconductivity, with the promise to explore Majorana modes and topological quantum computing.
Electronic properties and devices, Superconducting properties and materials
Nature Materials
Superconducting magic-angle twisted trilayer graphene with competing magnetic order and moiré inhomogeneities
Original Paper | Electronic properties and materials | 2025-05-21 20:00 EDT
Ayshi Mukherjee, Surat Layek, Subhajit Sinha, Ritajit Kundu, Alisha H. Marchawala, Mahesh Hingankar, Joydip Sarkar, L. D. Varma Sangani, Heena Agarwal, Sanat Ghosh, Aya Batoul Tazi, Kenji Watanabe, Takashi Taniguchi, Abhay N. Pasupathy, Arijit Kundu, Mandar M. Deshmukh
The microscopic mechanism of unconventional superconductivity in magic-angle twisted trilayer graphene is poorly understood. We show direct evidence for an in-plane magnetic order competing with the superconducting state motivated by theoretical proposals. We use two complementary electrical transport measurements. First, in statistically significant switching events in the superconducting state of magic-angle twisted trilayer graphene, we observe non-monotonic and hysteretic responses in the switching distributions as a function of temperature and in-plane magnetic field. Additionally, the system behaves like a network of Josephson junctions due to lattice-relaxation-induced moiré inhomogeneity. Second, in normal regions doped slightly away from the superconducting regime, hysteretic and linear positive magnetoresistance with the in-plane magnetic field shows evidence for an in-plane magnetic order. Furthermore, we estimate superfluid stiffness Js ≈ 0.15 K with strong temperature dependence and show a broadened Berezinskii-Kosterlitz-Thouless transition. Our observations may constrain possible intervalley-coherent magnetic orders and the superconductivity arising from its fluctuations.
Electronic properties and materials, Superconducting devices, Superconducting properties and materials
Nature Physics
Interplay between light and heavy electron bands in magic-angle twisted bilayer graphene
Original Paper | Electronic properties and devices | 2025-05-21 20:00 EDT
Rafael Luque Merino, Dumitru Călugăru, Haoyu Hu, Jaime Díez-Mérida, Andrés Díez-Carlón, Takashi Taniguchi, Kenji Watanabe, Paul Seifert, B. Andrei Bernevig, Dmitri K. Efetov
Recent studies have suggested that the strongly correlated flat bands of magic-angle twisted bilayer graphene may host coexisting light and heavy carriers. Although transport and spectroscopic measurements have hinted at this behaviour, distinct signatures of incoherent heavy carriers have not been reported. Here we provide evidence of this by performing thermoelectric transport measurements of magic-angle twisted bilayer graphene using the photo-thermoelectric effect in gate-defined p-n junctions. At low temperatures, we observe sign-preserving, filling-dependent oscillations of the Seebeck coefficient at non-zero integer fillings of the moiré superlattice. This suggests the preponderance of one carrier type even when the Fermi level is tuned through the charge neutrality point of the correlated states. At higher temperatures, the thermoelectric response provides evidence of strong electron correlations in the unordered, normal state. Our observations are explained by the interplay between light, long-lived electron states and heavy, short-lived hole excitations near the Fermi level of the symmetry-broken ground states. These findings are in qualitative agreement with the topological heavy fermion model.
Electronic properties and devices, Electronic properties and materials, Phase transitions and critical phenomena
Long optical coherence times in a rare-earth-doped antiferromagnet
Original Paper | Ferromagnetism | 2025-05-21 20:00 EDT
Masaya Hiraishi, Zachary H. Roberts, Gavin G. G. King, Luke S. Trainor, Jevon J. Longdell
The absorption spectra of rare-earth ions have very narrow linewidths. Even in solid-state crystals, exceedingly long coherence times have been observed for the spin and optical transitions of rare-earth-ion dopants. The influence of electronic and nuclear spins in the host crystal is a key factor limiting these coherence times. Here we suppress the effects of electron spins by using erbium dopants in a gadolinium vanadate host that is fully concentrated in electron spins but operated at sufficiently low temperatures that the spins form an antiferromagnetically ordered state. We achieve long optical coherence times and, furthermore, observe avoided crossings in the optical spectra, which are caused by strong coupling between the erbium ions and gadolinium magnons in the host crystal. This indicates the possibility of magnon-mediated microwave-to-optical quantum transduction using rare-earth ions, which would provide a connection between telecommunications technology and solid-state quantum devices operating in the microwave regime.
Ferromagnetism, Quantum optics, Quantum physics
Nature Reviews Materials
Multimaterial extrusion 3D printing printheads
Review Paper | Design, synthesis and processing | 2025-05-21 20:00 EDT
Nathan C. Brown, Daniel C. Ames, Jochen Mueller
Printheads are the cornerstone of material extrusion 3D printing systems, now capable of processing virtually any material – organic or inorganic. Multimaterial capabilities have further expanded their versatility, enabling coextrusion, mixing and material switching. Advanced multifunctional printhead features allow for nozzle size and shape adjustments, printhead rotation and in situ property modulation. These improvements enable unprecedented design complexity, higher throughput and the fabrication of intricate material compositions across multiple length scales. Applications span from architected metamaterials with tunable properties to functional tissue from living cells and soft robotics with integrated sensing. This Review provides a comprehensive overview of this rapidly evolving field, introducing eight archetypal printhead categories and their hybrids. It explores their role in materials design, ability to overcome processing limitations and impact on emerging applications. Additionally, it identifies open challenges and offers an outlook on the future of multimaterial 3D printing.
Design, synthesis and processing, Engineering, Materials science
Physical Review Letters
All Incompatible Measurements on Qubits Lead to Multiparticle Bell Nonlocality
Research article | Nonlocality | 2025-05-21 06:00 EDT
Martin Plávala, Otfried Gühne, and Marco Túlio Quintino
Bell nonlocality is a fundamental phenomenon of quantum physics as well as an essential resource for various tasks in quantum information processing. It is known that for the observation of nonlocality the measurements on a quantum system have to be incompatible, but the question of which incompatible measurements are useful, remained open. Here we prove that any set of incompatible measurements on qubits leads to a violation of a suitable Bell inequality in a multiparticle scenario, where all parties perform the same set of measurements. Since there exists incompatible measurements on qubits which do not lead to Bell nonlocality for two particles, our results demonstrate a fundamental difference between two-particle and multiparticle nonlocality, pointing at the superactivation of measurement incompatibility as a resource. In addition, our results imply that measurement incompatibility for qubits can always be certified in a device-independent manner.
Phys. Rev. Lett. 134, 200201 (2025)
Nonlocality, Quantum measurements
Run-and-Tumble Exact Work Statistics in a Lazy Quantum Measurement Engine: Stochastic Information Processing
Research article | Nonequilibrium statistical mechanics | 2025-05-21 06:00 EDT
Léa Bresque, Debraj Das, and Édgar Roldán
We introduce a single-qubit quantum measurement engine fuelled by backaction energy input. To reduce energetic costs associated with information processing, the measurement outcomes are only used with a prescribed laziness probability in the feedback step. As a result, we show that the work extracted over consecutive cycles is a second-order Markov process, analogous to a run-and-tumble process with transient anomalous diffusion. We derive exact analytical expressions for the work finite-time moments and first-passage-time statistics. Furthermore, we find the optimal laziness probability maximizing the mean power extracted per cycle.
Phys. Rev. Lett. 134, 200402 (2025)
Nonequilibrium statistical mechanics, Quantum measurements, Quantum thermodynamics, Random walks, Stochastic resetting, Stochastic thermodynamics, Quantum heat engines & refrigerators, Non-Markovian processes
Experimental Verifiable Multiclient Blind Quantum Computing on a Qline Architecture
Research article | Optical quantum information processing | 2025-05-21 06:00 EDT
Beatrice Polacchi, Dominik Leichtle, Gonzalo Carvacho, Giorgio Milani, Nicolò Spagnolo, Marc Kaplan, Elham Kashefi, and Fabio Sciarrino
The exploitation of certification tools by end users represents a fundamental aspect of the development of quantum technologies as the hardware scales up beyond the regime of classical simulability. Certifying quantum networks becomes even more crucial when the privacy of their users is exposed to malicious quantum nodes or servers as in the case of multiclient distributed blind quantum computing, where several clients delegate a joint private computation to remote quantum servers, such as federated quantum machine learning. In such protocols, security must be provided not only by keeping data hidden but also by verifying that the server is correctly performing the requested computation while minimizing the hardware assumptions on the employed devices. Notably, standard verification techniques fail in scenarios where the clients receive quantum states from untrusted sources such as in a recently demonstrated linear quantum network performing multiclient blind quantum computation. However, recent theoretical results provide techniques to verify blind quantum computations even in the case of untrusted state preparation. Equipped with such theoretical tools, in this Letter we provide the first experimental implementation of a multiclient verifiable blind quantum computing protocol in a distributed architecture. Our results represent novel perspectives for the verification of multitenant distributed quantum computation in large-scale networks.
Phys. Rev. Lett. 134, 200603 (2025)
Optical quantum information processing, Quantum computation, Quantum networks, Quantum optics, Quantum protocols, Quantum verification
Type II Superstring Amplitude at One-Loop and Transcendentality
Effective field theory | 2025-05-21 06:00 EDT
Emiel Claasen and Mehregan Doroudiani
We calculate the four-graviton scattering amplitude in Type II superstring theory at one loop up to seventh order in the low-energy expansion through the recently developed iterated integral formalism of Modular Graph Functions (MGFs). The machinery of the novel method allows us to propose a general form of the amplitude, which suggests that the expansion is expressible in terms of single-valued multiple zeta values and logarithmic derivatives of the Riemann zeta function at positive and negative odd integers. Furthermore, we comment on the transcendental behavior of the amplitude.
Phys. Rev. Lett. 134, 201601 (2025)
Effective field theory, Perturbation theory, Quantum gravity, Scattering amplitudes, Strings & branes, Supergravity, Supersymmetric field theories
Comprehensive Measurement of the Reactor Antineutrino Spectrum and Flux at Daya Bay
Research article | Beta decay | 2025-05-21 06:00 EDT
F. P. An et al. (Daya Bay Collaboration)
This Letter reports the precise measurement of the reactor antineutrino spectrum and flux based on the full dataset of $4.7\times{}{10}^{6}$ inverse-beta-decay candidates collected at Daya Bay near detectors. Expressed in terms of the inverse-beta-decay yield per fission, the antineutrino spectra from all reactor fissile isotopes and the specific $^{235}\mathrm{U}$ and $^{239}\mathrm{Pu}$ isotopes are measured with 1.3%, 3%, and 8% uncertainties, respectively, near the 3 MeV spectrum peak in reconstructed energy, reaching the best precision in the world. The total antineutrino flux and isotopic $^{235}\mathrm{U}$ and $^{239}\mathrm{Pu}$ fluxes are precisely measured to be $5.84\pm{}0.07$, $6.16\pm{}0.12$, and $4.16\pm{}0.21$ in units of ${10}^{- 43}\text{ }\text{ }{\mathrm{cm}}^{2}/\text{fission}$. These measurements are compared with the Huber-Mueller model, the reevaluated conversion model based on the Kurchatov Institute measurement, and the latest summation model (SM2023). The Daya Bay flux shows good consistency with the Kurchatov Institute and SM2023 models but disagrees with the Huber-Mueller model. The Daya Bay spectrum, however, disagrees with all model predictions.
Phys. Rev. Lett. 134, 201802 (2025)
Beta decay, Neutrino interactions, Neutrinos
Modular Variable Laser Cooling for Efficient Entropy Extraction
Research article | Coherent control | 2025-05-21 06:00 EDT
B. de Neeve, T.-L. Nguyen, A. Ferk, T. Behrle, F. Lancellotti, M. Simoni, S. Welte, and J. P. Home
A new laser-based cooling scheme approaches the maximum efficiency that is theoretically achievable.
Phys. Rev. Lett. 134, 203603 (2025)
Coherent control, Optical pumping, Trapped ions, Atom & ion cooling, Bayesian methods, Dissipative particle dynamics, Phase space methods
Drift-Energy Replacement Effect in Multi-ion Magnetized Plasma
Research article | Plasma fusion | 2025-05-21 06:00 EDT
M. E. Mlodik, E. J. Kolmes, and N. J. Fisch
Fast rotation can improve the stability and confinement of fusion plasmas. However, to maintain a rapidly rotating fusion plasma in steady state, significant energy must be invested in spinning up each incoming fuel ion. We show here that, under the right circumstances, collisional cross-field radial fueling can directly transfer drift energy between outgoing and incoming ions without the need for external power recirculation, thereby reducing the energy costs of maintaining the rotation.
Phys. Rev. Lett. 134, 205101 (2025)
Plasma fusion, Plasma transport, Fusion reactors, Magnetic mirrors & traps, Magnetized plasma, First-principles calculations in plasma physics
Unified Interface Model for Dissipative Transport of Bosons and Fermions
Research article | Critical phenomena | 2025-05-21 06:00 EDT
Y. Minoguchi, J. Huber, L. Garbe, A. Gambassi, and P. Rabl
Dissipative transport of both fermionic and bosonic particles in a one-dimensional lattice belongs to the Kardar-Parisi-Zhang universality class.
Phys. Rev. Lett. 134, 207102 (2025)
Critical phenomena, Nonequilibrium statistical mechanics, Open quantum systems & decoherence, Quantum kinetic theory, Asymmetric simple exclusion process, Dissipative particle dynamics, Fokker-Planck equation, Full counting statistics, Kardar-Parisi-Zhang equation, Master equation, Quantum Monte Carlo, Quantum master equation
Morphogenesis of Cheese Flowers through Scraping
Research article | Fracture | 2025-05-21 06:00 EDT
J. Zhang, A. Ibarra, B. Roman, and M. Ciccotti
Scraping the surface of a Tête de Moine cheese wheel produces frilly ribbons whose flower-like forms depend on the local friction.
Phys. Rev. Lett. 134, 208201 (2025)
Fracture, Friction, Morphogenesis, Plastic deformation, Shear deformation, Tribology
Physical Review X
Topological Phases with Average Symmetries: The Decohered, the Disordered, and the Intrinsic
Research article | Open quantum systems & decoherence | 2025-05-21 06:00 EDT
Ruochen Ma, Jian-Hao Zhang, Zhen Bi, Meng Cheng, and Chong Wang
Symmetry-protected topological phases can persist in mixed states despite disorder and noise, provided ensemble-averaged symmetry is maintained. This reveals new phases unique to mixed states, enhancing robustness for quantum technologies.
Phys. Rev. X 15, 021062 (2025)
Open quantum systems & decoherence, Symmetry protected topological states, Topological order, Topological phases of matter, Disordered systems, Topology
Minimal Fractional Topological Insulator in Half-Filled Conjugate Moiré Chern Bands
Research article | Quantum spin Hall effect | 2025-05-21 06:00 EDT
Chao-Ming Jian, Meng Cheng, and Cenke Xu
A new minimal model explains puzzling signs of the fractional quantum spin Hall effect in moiré materials, offering a simpler, unified framework for quantum many-body topology and transport behavior.
Phys. Rev. X 15, 021063 (2025)
Quantum spin Hall effect, Topological insulators, Topological phases of matter, Bilayer films, Topological materials, Transition metal dichalcogenides, Two-dimensional electron system
arXiv
Hydrogen trapping in sub-stoichiometric niobium and vanadium carbide precipitates in high-strength steels
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
High strength steels (HSS) are widely used in aerospace industries but they can be susceptible to hydrogen embrittlement (HE), a phenomenon that with the ingress of a small amount of hydrogen, the materials can experience a ductile to brittle transition. Secondary carbide precipitates play a crucial role in reducing HE in steels by providing strong hydrogen traps, reducing diffusible hydrogen atoms that are detrimental to the steel ductility. Among the secondary carbide precipitates, sub-stoichiometric vanadium and niobium carbides contain high concentrations of carbon vacancies, which serve as robust hydrogen traps that greatly reduced diffusible hydrogen atoms, beneficial for the HE resistivity. This study investigated hydrogen trapping energies in VCx and NbCx and revealed that sub-stoichiometry plays a role in hydrogen trapping ability. Further examination of hydrogen trapping in vacancies revealed the charge density at vacancy can affect the bonding between hydrogen and neighboring V/Nb atoms. Additionally, the vacancy configurations in VCx and NbCx with varying x plays a role in hydrogen diffusional barriers inside them. Carbides with more vacancies possess reduced hydrogen diffusional barriers within them. In conclusion, the vacancies in certain carbide compounds can enhance both the trapping energy and possibly trapping capacity of hydrogen atoms, ultimately reducing the susceptibility of HSS to HE.
Materials Science (cond-mat.mtrl-sci)
Ordering the topological order in the fractional quantum Hall effect
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-22 20:00 EDT
Meng Cheng, Seth Musser, Amir Raz, Nathan Seiberg, T. Senthil
We discuss the possible topological order/topological quantum field theory of different quantum Hall systems. Given the value of the Hall conductivity, we constrain the global symmetry of the low-energy theory and its anomaly. Specifically, the one-form global symmetry and its anomaly are presented as the organizing principle of these systems. This information is powerful enough to lead to a unique minimal topological order (or a small number of minimal topological orders). Almost all of the known experimentally discovered topological orders are these minimal theories. Since this work is interdisciplinary, we made a special effort to relate to people with different backgrounds by providing translations between different perspectives.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), High Energy Physics - Theory (hep-th)
83 pages, 4 figures, 2 tables
Monopoles, Dirac strings and Magnetic Noise in Model Spin Ice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-22 20:00 EDT
A. Huster Zapke, P. C. W. Holdsworth
Using the Dirac string formalism for monopoles we expose an extensive analogy between magnetic monopole excitations in the dumbbell model of spin ice and those of the vacuum. In both cases the Dirac strings are defined in the space-time of monopole trajectories which are simulated in spin ice using transition graphs between initial and final configurations. The Stanford experiment for Dirac monopole detection is reconstructed in spin ice using the fragmentation procedure. The setup is then extended to simulate magnetic noise experiments using stochastic dynamics. It is shown that the noise from the monopoles and their constraining strings can be separated and that the correlated signal over long times comes largely from the constraining strings rather than from the monopoles themselves.
Strongly Correlated Electrons (cond-mat.str-el)
Crystal structure, magnetic properties and magnetocaloric performance of RE$_{5}$Rh$_2$In$_4$ (RE = Gd-Tm) compounds
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Altifani Rizky Hayyu, Stanisław Baran, Aleksandra Deptuch, Andrzej Szytuła
Polycrystalline samples of the RE$ _{5}$ Rh$ _2$ In$ _4$ (RE = Gd–Tm) intermetallics have been investigated by means of X-ray diffraction (XRD) as well as by DC and AC magnetometric measurements. The XRD data confirm that the compounds crystallize with the orthorhombic Lu$ _{5}$ Ni$ _2$ In$ _4$ -type structure (space group Pbam, No. 55). With decreasing temperature, RE$ _{5}$ Rh$ _2$ In$ _4$ spontaneously order magnetically with the critical temperatures of magnetic order equal to 10.6, 14.2, 15.4, 7.2, 5.9 and 4.9 K for RE = Gd, Tb, Dy, Ho, Er and Tm, respectively. The compounds have complex magnetic properties, showing features characteristic of both ferro- and antiferromagnetic orderings. Moreover, the magnetic properties change with increasing number of the 4f electrons from predominantly ferromagnetic in Gd$ _{5}$ Rh$ _2$ In$ _4$ to predominantly antiferromagnetic in Tm$ _{5}$ Rh$ _2$ In$ 4$ . The magnetic data indicate that only the rare earth atoms carry magnetic moments. The maximum magnetic entropy change ($ -\Delta S{M}^{max}$ ) at the 0-9 T magnetic flux density change ($ \Delta \mu_0 H$ ) equals 12.4 J$ \cdot$ kg$ ^{-1}\cdot$ K$ ^{-1}$ at 17 K for Gd$ _{5}$ Rh$ _2$ In$ _4$ , 11.3 J$ \cdot$ kg$ ^{-1}\cdot$ K$ ^{-1}$ at 28 K for Tb$ _{5}$ Rh$ _2$ In$ _4$ , 13.1 J$ \cdot$ kg$ ^{-1}\cdot$ K$ ^{-1}$ at 19 K for Dy$ _{5}$ Rh$ _2$ In$ _4$ , 16.4 J$ \cdot$ kg$ ^{-1}\cdot$ K$ ^{-1}$ at 12 K for Ho$ _{5}$ Rh$ _2$ In$ _4$ , 15.3 J$ \cdot$ kg$ ^{-1}\cdot$ K$ ^{-1}$ at 8 K for Er$ _{5}$ Rh$ _2$ In$ _4$ and 12.6 J$ \cdot$ kg$ ^{-1}\cdot$ K$ ^{-1}$ at 6.5 K for Tm$ _{5}$ Rh$ _2$ In$ _4$ . For a selected rare earth element (RE), the member of the RE$ _{5}$ Rh$ _2$ In$ 4$ family of compounds reaches the highest $ -\Delta S{M}^{max}$ value, when compared with its RE$ _{5}$ T$ _2$ In$ _4$ (T = Ni, Pd, Pt) isostructural analogues, making the RE$ _{5}$ Rh$ _2$ In$ _4$ intermetallics a good choice for application in low-temperature magnetic refrigeration.
Materials Science (cond-mat.mtrl-sci)
17 pages, 8 figures
Flux Jumps up to 17 T in ReBCO Tape Stack Cables and their Suppression with Increased Intertape Spacing
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-22 20:00 EDT
Tushar Garg (1), Mike D. Sumption (1), Milan Majoros (1), Edward Collings (1), Jan Jaroszynski (2), Eun-Sang Choi (2) ((1) Center for Superconducting and Magnetic Materials, Materials Science Department, Ohio State University, (2) National High Magnetic Field Laboratory)
The magnetization of ReBCO tape stacks and tape stack cables in high magnetic fields (up to 30 T) are not commonly reported. Here we report magnetization measurements of tape stack cables in magnetic fields up to 30 T at 4.2 K. We observed that flux jumps, commonly relegated to low field regimes for single tapes, persisted up to 17 T in tape stacks, an effect which could have substantial technological relevance for high field applications including fusion devices or accelerator magnets. On the other hand, with the use of small spacers, we could suppress flux jump behavior, in some cases eliminating jumps entirely. Our findings provide critical insights for the optimization of designs for ReBCO cables for high-field applications, including fusion magnets and particle accelerators.
Superconductivity (cond-mat.supr-con), Accelerator Physics (physics.acc-ph)
9 pages, 3 figures, 1 table
Structural and Bonding Insights into B8Cu3- Clusters: A DFT Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
In this study, we employ density functional theory (DFT) to investigate the structural and electronic properties of B8Cu3- clusters-boron-based frameworks doped with three copper atoms. The results indicate that the lowest-energy structure features a vertical Cu3 triangle supported on a B$ _8$ wheel geometry, whereas the horizontally supported configuration is 3.0 (5.6) kcal/mol higher in energy at the PBE0 (wB97X) functional. Electron localization function (ELF) and Mulliken population analyses reveal that the most stable isomer exhibits strong Cu-B interactions and significant electron delocalization, which contribute to its enhanced stability. Localized orbital locator (LOL) maps further support this finding by showing pronounced electron localization around the Cu3 unit in the more stable structure. These insights highlight the possible role of Cu-centered multicenter bonding in stabilizing boron-based nanoclusters.
Materials Science (cond-mat.mtrl-sci)
5 pages, 2 tables, 4 figures
Perpendicularly magnetized Tb/Co multilayers featuring tilted uniaxial anisotropy: Experiments and modeling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
J. C. Rodriguez E., L. Avilés-Félix, M. H. Aguirre, L. M. Rodriguez, D. Salomoni, S. Auffret, R. C. Sousa, I. L. Prejbeanu, A. E. Bruchhausen, E. De Biasi, J. Curiale
Rare earth/transition metal (RE/TM) multilayers with perpendicular magnetic anisotropy are key ingredients for the development of spintronic applications. Their compensation temperature depends on the ratio of the thicknesses of rare earth and transition metal, allowing their magnetic properties to be tuned with temperature while maintaining their anisotropy even in nanometer-scale devices. In this work, we performed a thorough structural characterization and systematically investigate the magnetic properties of a whole family of ferrimagnetic [Tb/Co]$ _{\times 5}$ multilayers varying the Tb thickness in the range of 0.4 nm - 1.25 nm. A linear dependence of the compensation temperature on the Tb layer thickness was observed. Moreover, a uniaxial anisotropy constant of 330$ \pm$ 30 kJ/m$ ^3$ , which is close to the values reported by other authors, was estimated. Additionally, we proposed a model to gain a better understanding of the angular dependence of the magnetization loops and the linear dependence of the compensation temperature. We present strong evidence demonstrating that the perpendicular anisotropy must be tilted away from the perpendicular axis in order to explain the observed features, particularly the hysteresis in the in-plane loops. Our work advances the understanding of DC magnetic properties in thin RE/TM ferrimagnetic films, which has the potential to impact different fields where these materials are involved.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 7 figures
Josephson junction and inductor models in ADS
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-22 20:00 EDT
This note is a follow up to arXiv:2408.07861, describing how to construct Josephson junction, inductor, and mutual inductance models using components that are available in the Keysight ADS core library.
Superconductivity (cond-mat.supr-con), Applied Physics (physics.app-ph)
3 pages, 4 figures
Coarse grained descriptions of the dynamics of yielding of amorphous solids under cyclic shear
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-22 20:00 EDT
Debargha Sarkar, Jishnu N. Nampoothiri, Muhittin Mungan, Jack T. Parley, Peter Sollich, Srikanth Sastry
Recent computer simulations reveal several intriguing features in the evolution of properties of amorphous solids subjected to repeated cyclic shear deformation. These include the divergence of the number of cycles to reach steady states as the yielding point is approached, a non-monotonic change of properties with cycles, and the possibility of a spectrum of frozen states. Theoretical attempts to capture these properties through simple models, including the Ehrenfest model describing a random walk in a confining potential, have met partial success. Here, we show that incorporating the influence of mechanical noise through a feedback term leads to a genuine dynamical transition with characteristics reflecting those of yielding. Coarse graining the dynamics into a small number of variables leads to new insights regarding the dynamics of yielding.
Statistical Mechanics (cond-mat.stat-mech)
Statistical field theory of equilibrium amorphous solids and the intrinsic heterogeneity distributions that characterize them
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-22 20:00 EDT
Paul M. Goldbart (Stony Brook University)
A rich variety of amorphous solids are found in nature and technology, including ones formed via the vulcanization of long, flexible molecules. A special class – those featuring a wide gap between the long timescales over which constraints in them release and the much shorter timescales over which their unconstrained freedoms relax – exhibit states of thermodynamic equilibrium and are thus amenable to the framework of equilibrium statistical physics. The approach reviewed here is the least specific – and thus the most general – approach to the statistical mechanics of equilibrium amorphous solid-formers: statistical field theory. An overview is given of the key elements and results of this theory. The field of the theory is constructed to detect and diagnose the amorphous solid state. Its form turns out to be unusual, in ways that are essential for its application, so it is examined in detail, as is the form of the field theory controlling the field. What this theory can predict for the equilibrium properties of amorphous solids is then discussed, including: the transition to the amorphous solid state and the heterogeneity of the resulting solid; the impact of fluctuations on the transition and connections with percolation theory; the pattern of symmetry-breaking and the nature of the resulting elasticity; and field correlations and the information they provide. Emphasis is placed on the idea, peculiar to amorphous solids, that their equilibrium states are naturally characterized in terms of distributions that capture the intrinsic spatial heterogeneity of the thermal motions of their constituents. The theory’s field has an internal structure that subtly encodes this information, via the wave-vector dependencies of the average field and its correlations. Reflections are made on the applicability of theses ideas and results to a range of amorphous solids and related systems.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
29 pages
Superconducting vacancy-ordered rock-salt NbO films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-22 20:00 EDT
Jeong Rae Kim, Sandra Glotzer, Evan Krysko, Matthew R. Barone, Jinkwon Kim, Salva Salmani-Rezaie, Adrian Llanos, Joseph Falson
We report molecular beam epitaxy synthesis of vacancy-ordered rocksalt NbO thin films which display superconductivity. A comparative study of substrates identifies Al$ _2$ O$ 3$ (0001) as the optimal platform for realizing high-quality, single-phase films when growing at temperatures exceeding 1000 $ ^\circ$ C. The controlled NbO films exhibit superconductivity with critical temperatures up to $ T\mathrm{c}$ = 1.37 K, comparable to bulk single crystals. This work addresses the fundamental bottlenecks encountered in the high-temperature epitaxy of compounds with uncommon oxidation states, while expanding the scope of available thin-film superconductors.
Superconductivity (cond-mat.supr-con)
12 pages, 7 figures
Observation of Topological Hall Effect in Synthetic Antiferromagnetic Skyrmion System
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-22 20:00 EDT
Xinbao Geng, Guanqi Li, Zhongxiang Zhang, Wenjing Hu, Wenjing Zhong, Xiaoming Xiong, Yongbing Xu, Zhendong Chen, Junlin Wang, Xiangyu Zheng, Jing Wu
Synthetic antiferromagnetic (SAF) skyrmions have emerged as promising candidates for next-generation high-speed and highly integrated spintronic devices, owing to their exceptional properties such as high driving velocity, nanoscale dimensions, and the absence of the skyrmion Hall effect. In this work, we report the observation of the topological Hall effect in both compensated and non-compensated synthetic antiferromagnetic skyrmion systems based on [Pt/Co/Ru]2 bilayers. The antiferromagnetic skyrmions are demonstrated to be robust in these synthetic antiferromagnets under zero-field. Our first principal calculations and micromagnetic simulations demonstrate that the formation of the antiferromagnetic skyrmions are due to nonuniformity of RKKY coupling associated with the proximity effect induced magnetic moments in the Pt and Ru layers. The skyrmions in the Pt and Ru layers adjacent to the Co layers lead to the observed topological Hall effect. This work not only provides insight into the effect of the magnetic proximity effect and RKKY coupling to the SAF skyrmions, but also an effective detection method for the SAF skyrmion systems, thereby laying a foundation for the practical application of antiferromagnetic skyrmions in spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Two-Terminal Electrical Detection of the Néel Vector via Longitudinal Antiferromagnetic Nonreciprocal Transport
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Guozhi Long, Hui Zeng, Mingxiang Pan, Wenhui Duan, Huaqing Huang
We propose a robust two-terminal electrical readout scheme for detecting the Néel vector orientation in antiferromagnetic (AFM) materials by leveraging longitudinal nonreciprocal transport driven by quantum metric dipoles. Unlike conventional readout mechanisms, our approach does not require spin-polarized electrodes, tunneling junctions, or multi-terminal geometries, offering a universal and scalable solution for AFM spintronics. As examples, we demonstrate pronounced second-order longitudinal nonlinear conductivity (LNC) in two-dimensional (2D) MnS and 3D CuMnAs, both of which exhibit clear sign reversal of LNC under 180$ ^\circ$ Néel vector reorientation. We show that this LNC is predominantly governed by the intrinsic, relaxation-time-independent quantum metric mechanism rather than the extrinsic nonlinear Drude effect. Our findings provide a practical and material-general pathway for electrically reading AFM memory states, with promising implications for next-generation AFM spintronic technologies.
Materials Science (cond-mat.mtrl-sci)
Multicrossmodal Automated Agent for Integrating Diverse Materials Science Data
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Adib Bazgir, Rama chandra Praneeth Madugula, Yuwen Zhang
We introduce a multicrossmodal LLM-agent framework motivated by the growing volume and diversity of materials-science data ranging from high-resolution microscopy and dynamic simulation videos to tabular experiment logs and sprawling literature archives. While recent AI efforts have accelerated individual tasks such as property prediction or image classification, they typically treat each modality in isolation, leaving rich cross-modal correlations unexplored and forcing researchers to perform laborious manual integration. Moreover, existing multimodal foundation models often require expensive retraining or fine-tuning on domain data, and current multi-agent systems in materials informatics address only narrow subtasks. To overcome these obstacles, we design a coordinated team of specialized LLM agents, each equipped with domain-adapted prompts and plugins that project their outputs into a shared embedding space. A dynamic gating mechanism then weights and merges these insights, enabling unified reasoning over heterogeneous inputs without ever modifying the underlying LLM weights. We validate our approach on challenging case studies and demonstrate substantial gains in retrieval accuracy (85%), captioning fidelity, and integrated coverage (35%) compared to single-modality and zero-shot baselines. Our work paves the way for AI digital researchers capable of bridging data silos and accelerating the materials-discovery cycle. The code is available at this https URL.
Materials Science (cond-mat.mtrl-sci)
How to exploit driving and dissipation to stabilize and manipulate quantum many-body states
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-22 20:00 EDT
We review the basic concepts of quantum fluids of light and the different techniques that have been developed to exploit driving and dissipation to stabilize and manipulate interesting many-body states. In the weakly interacting regime, this approach has allowed to study, among other, superfluid light, non-equilibrium Bose-Einstein condensation, photonic analogs of Hall effects, and is opening the way towards the realization of a new family of analog models of gravity. In the strongly interacting regime, the recent observations of Mott insulators and baby Laughlin fluids of light open promising avenues towards the study of novel strongly correlated many-body states.
Quantum Gases (cond-mat.quant-gas)
Bridging Two Dimensions: Luminescent Sensors at the Intersection of Temperature and Pressure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Lukasz Marciniak, Maja Szymczak, Przemyslaw Wozny, Marcin Runowski
Luminescence thermometry and manometry are exponentially growing areas dealing with the optical detection of temperature and pressure, respectively, being appealing alternatives for conventional thermometers and manometers. The main benefit of luminescent thermometers and manometers is a possibility of remote temperature and/or pressure monitoring, in contrast to conventional gauges. Moreover, the use of luminescent nanoparticles as temperature/pressure sensors allow detection in micron- and nano-sized areas, previously inaccessible for conventional gauges. Therefore, the combination of both functionalities in a single material is highly appealing, as has been shown in a growing number of reports in the last years. Moreover, the bifunctional pressure and temperature sensors, operating with multiple independent spectroscopic parameters, allow simultaneous and distinct pressure and temperature readouts. However, the development of such truly bifunctional and reliable sensors is very challenging and rarely reported. This review summarizes the current status in the field, focusing on the sensing strategy and the selection of optically active sensor materials appropriate for a given application, including their sensitivity, spectral range of interest and pressure/temperature (in)dependence.
Materials Science (cond-mat.mtrl-sci)
Manipulating the hydrogen-induced insulator-metal transition through artificial microstructure engineering
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-22 20:00 EDT
Xuanchi Zhou, Xiaohui Yao, Wentian Lu, Jinjian Guo, Jiahui Ji, Lili Lang, Guowei Zhou, Chunwei Yao, Xiaomei Qiao, Huihui Ji, Zhe Yuan, Xiaohong Xu
Hydrogen-associated filling-controlled Mottronics within electron-correlated system provides a groundbreaking paradigm to explore exotic physical functionality and phenomena. Dynamically controlling hydrogen-induced phase transitions through external fields offers a promising route for designing protonic devices in multidisciplinary fields, but faces high-speed bottlenecks owing to slow bulk diffusion of hydrogens. Here, we present a promising pathway to kinetically expedite hydrogen-related Mott transition in correlated VO2 system by taking advantage of artificial microstructure design. Typically, inclined domain boundary configuration and cR-faceted preferential orientation simultaneously realized in VO2/Al2O3 (102) heterostructure significantly lower the diffusion barrier via creating an unobstructed conduit for hydrogen diffusion. As a result, the achievable switching speed through hydrogenation outperforms that of counterpart grown on widely-reported c-plane Al2O3 substrate by 2-3 times, with resistive switching concurrently improved by an order of magnitude. Of particular interest, an anomalous uphill hydrogen diffusion observed for VO2 with a highway for hydrogen diffusion fundamentally deviates from basic Fick’s law, unveiling a deterministic role of hydrogen spatial distribution in tailoring electronic state evolution. The present work not only provides a versatile strategy for manipulating ionic evolution, endowing with great potential in designing high-speed protonic devices, but also deepens the understanding of hydrogen-induced Mott transitions in electron-correlated system.
Strongly Correlated Electrons (cond-mat.str-el)
Rare-Earth Nitrides: Fundamental Advances and Applications in Cryogenic Electronics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
W. F. Holmes-Hewett, J. D. Miller, H. G. Ahmad, S. Granville, B. J. Ruck
Driven by the pursuit of high-performance electronic devices, research into novel materials with properties appropriate for cryogenic applications has unveiled the exceptional properties of the rare-earth nitride series of intrinsic ferromagnetic semiconductors. Here we report on the field focusing on developments, since the most recent comprehensive review [1], which enable applications in cryogenic electronic devices.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Bonding relay for room-temperature oxide plasticity like metals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Xiangkai Chen, Yuhong Li, Xiaofei Zhu, Yun-Long Tang, Shi Liu
Oxides have long been regarded as intrinsically brittle due to their strong, directional ionic or covalent bonds, in stark contrast to the ductile behavior of metals, where delocalized electron sharing enables plasticity through facile dislocation glide. Here, we challenge this paradigm by demonstrating that typical oxides, such as SrTiO3 and MgO, can exhibit room-temperature plasticity with pronounced crystallographic anisotropy. Through an integrated approach combining ab initio calculations, large scale molecular dynamics simulations, and experimental nanoindentation, we identify a universal structural criterion enabling room-temperature oxide plasticity: the presence of alternating positively and negatively charged atomic layers along specific slip directions, specifically the (1-10)[110] orientation in perovskite and rocksalt oxides. This charge alternating configuration enables a bonding relay mechanism, in which sequential bond breaking and reformation across the slip plane accompanied by interlayer persistent bonds mimics multi centered interactions in metals, thereby facilitating dislocation motion without catastrophic failure. Our findings reveal a previously unrecognized pathway to achieving metal-like plasticity in oxides and establish a structural design principle for engineering flexible and mechanically resilient oxide materials.
Materials Science (cond-mat.mtrl-sci)
Multisetting protocol for Bell correlated states detection with spin-$f$ systems
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-22 20:00 EDT
Arkadiusz Kobus, Xinwei Li, Mariusz Gajda, Li You, Emilia Witkowska
We propose a multisetting protocol for the detection of two-body Bell correlations, and apply it to spin-nematic squeezed states realized in $ f$ pairs of SU(2) subsystems within spin-$ f$ atomic Bose-Einstein condensates. Experimental data for $ f=1$ , alongside with numerical simulations using the truncated Wigner method for $ f=1,,2,,3$ , demonstrate the effectiveness of the proposed protocol. Our findings extend the reach of multisetting Bell tests in ultracold atomic system, paving the way for extended quantum information processing in high-spin ensemble platforms.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
Stabilization of Martensite and Austenite Phases and Realization of Two-way Martensitic Transition in Co-Ni-Ga Ferromagnetic Shape Memory Alloy Nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Debraj Mahata, Ananthakrishnan Srinivasana
Three sets of Co-Ni-Ga alloy nanoparticles have been synthesized by a template-free chemical route. Structural, morphological, shape memory, and magnetic properties of room temperature martensite (M) phase, dual (M + secondary $ \gamma$ ) phase and austenite (A) phase Co-Ni-Ga nanoparticles are reported. Temperature-dependent XRD analysis revealed that $ Co_{36}Ni_{36}Ga_{28}$ nanoparticles exhibiting a single M phase at room temperature, completely transform to A phase at $ \sim1000$ K. Upon cooling to room temperature, the A phase transforms back to single M phase, confirming the two-way martensitic transition in Co-Ni-Ga nanoparticles. Structural analysis shows that the $ \gamma$ -phase does not influence the martensitic transition of bi-phasic (M + $ \gamma$ ) $ Co_{41}Ni_{34}Ga_{25}$ nanoparticles. These nanoparticles display saturation magnetization ranging from 2.9 emu/g to 15.3 emu/g at room temperature. The $ \gamma$ phase could be introduced in A phase $ Co_{44}Ni_{26}Ga_{30}$ nanoparticles when heated up to 1073 K. Curie temperatures of A and M phases are higher than the martensitic transition temperatures in all the samples, qualifying them as ferromagnetic shape memory alloy nanoparticles. Observation of M $ \leftrightarrow$ A phase transition, Co-Ni-Ga nanoparticles with tunable magnetic properties make them excellent candidates for low and high temperature nanoactuators and other ferromagnetic shape memory applications.
Materials Science (cond-mat.mtrl-sci)
Procedure of tuning up a three-site artificial Kitaev chain based on transmon measurements
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-22 20:00 EDT
Xiaozhou Yang, Zhaozheng Lyu, Xiang Wang, Enna Zhuo, Yunxiao Zhang, Duolin Wang, Yukun Shi, Yuyang Huang, Bing Li, Xiaohui Song, Peiling Li, Bingbing Tong, Ziwei Dou, Jie Shen, Guangtong Liu, Fanming Qu, Li Lu
Artificial Kitaev chains (AKCs), formed of quantum dot-superconductor linear arrays, provide a promising platform for hosting Majorana bound states (MBSs) and implementing topological quantum computing. The main challenges along this research direction would include the tuning up of AKCs for hosting MBSs and the readout of the parity of the chains. In this work, we present a step-by-step procedure for tuning up a three-site AKC to its sweet spots based on the spectra of a transmon circuit which is integrated with the chain for the purpose of reading out the parity of the chain. The signatures of the transmon’s plasma modes in each step, particular those related to the appearance of MBSs in the chain, will be given. We find that the sweet spots in a three-site AKC can be classified into three types based on the relative strengths of elastic cotunneling (ECT) and crossed Andreev reflection (CAR): ECT-dominated sweet spots, genuine sweet spots and CAR-dominated sweet spots. We show that the ECT-dominated and CAR-dominated sweet spots can be more conveniently accessed and utilized in transmon-based measurements.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Subgap pumping of antiferromagnetic Mott insulators: photoexcitation mechanisms and applications
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-22 20:00 EDT
Radu Andrei, Mingyao Guo, Mustafa Ali, Hoon Kim, Richard D. Averitt, David Hsieh, Eugene Demler
We study the behavior of the 2D repulsive Hubbard model on a square lattice at half filling, under strong driving with ac electric fields, by employing a time-dependent Gaussian variational approach. Within the same theoretical framework, we analytically obtain the conventional Keldysh crossover between multiphoton and tunneling photoexcitation mechanisms, as well as two new regimes beyond the Keldysh paradigm. We discuss how dynamical renormalization of the Mott-Hubbard gap feeds back into the photoexcitation process, modulating the carrier generation rate in real time. The momentum distribution of quasiparticle excitations immediately after the drive is calculated, and shown to contain valuable information about the generation mechanism. Finally, we discuss experimental probing of the pump-induced nonequilibrium electronic state.
Strongly Correlated Electrons (cond-mat.str-el)
Multiplexed holographic molecular binding assays with internal calibration standards
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-22 20:00 EDT
Kaitlynn Snyder, Andrew D. Hollingsworth, Fook Chiong Cheong, Rushna Quddus, David G. Grier
Holographic molecular binding assays detect macromolecules binding to colloidal probe beads by monitoring nanometer-scale changes in the beads’ diameters with holographic microscopy. Measured changes are interpreted with Maxwell Garnett effective-medium theory to infer the surface coverage of analyte molecules and therefore to measure the analyte concentration in solution. The precision and accuracy of those measurements can be degraded by run-to-run instrumental variations, which introduce systematic errors in the holographic characterization measurements. We detect and mitigate these errors by introducing a class of inert reference beads whose polymer brush coating resists macromolecular binding. The holographically measured diameter and refractive index of those beads serve as internal standards for THC measurements. To characterize the reference beads, we introduce a general all-optical method to measure the grafting density of the polymer brush that combines holographic characterization of the bead diameter with a refractometry measurement of the polymer’s specific volume. The latter technique shows the specific volume of poly(ethylene oxide) to be 1.308(4) cubic nanometers per kilodalton. We use this suite of techniques to demonstrate a multiplexed immunoassay for immunoglobulin G (IgG) whose success validates the effective-medium analysis of holographic characterization measurements. Internal negative controls provided by the reference beads are validated by negative control measurements on alcohol dehydrogenase (ADH), which has a similar molecular weight to IgG but does not bind to the probe beads’ binding sites.
Soft Condensed Matter (cond-mat.soft), Optics (physics.optics)
9 pages, 6 figures
Density modulations in active colloidal systems through orthogonal propulsion control and sensory delays
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-22 20:00 EDT
Ueli Töpfer, Maximilian R. Bailey, Sanjay Schreiber, Federico Paratore, Lucio Isa
Recent advancements in active colloidal systems aim to mimic key characteristics of biological microswimmers, particularly their adaptive motility in response to environmental changes. While many approaches rely on externally imposing a propulsive force, achieving true autonomous and self-regulating adaptation to the environment remains limited. In this study, we develop and analyze Janus microswimmers driven by electrohydrodynamic flows that autonomously adjust their propulsion dynamics in response to varying illumination conditions. Our Janus particles are silica colloids partially coated with titania, which self-propel via induced-charge electrophoresis (ICEP) under uniform AC electric fields. Since titania is photoconductive, it increases its conductivity under UV illumination, which thereby regulates the propulsion velocity independently of and orthogonally to the applied electric field. Crucially, the velocity adaptation requires a finite time. This sensory delay, which we systematically characterize, leads to enhanced microswimmer localization in response to spatiotemporal light modulations compared to the typical case of instantaneous response considered for synthetic microswimmers. By harnessing these dynamics, akin to those of biological microswimmers, we exert precise control over both local and global particle behavior, presenting novel opportunities for adaptive active matter systems.
Soft Condensed Matter (cond-mat.soft)
Observation of Body-Centered Cubic Iron above 200 Gigapascals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Zuzana Konopkova, Eric Edmund, Orianna B Ball, Agnes Dewaele, Helene Ginestet, Rachel J Husband, Nicolas Jaisle, Cornelius Strohm, Madden S Anae, Daniele Antonangeli, Karen Appel, Marzena Baron, Silvia Boccato, Khachiwan Buakor, Julien Chantel, Hyunchae Cynn, Anand P Dwivedi, Lars Ehm, Konstantin Glazyrin, Heinz Graafsma, Egor Koemets, Torsten Laurus, Hauke Marquardt, Bernhard Massani, James D McHardy, Malcolm I McMahon, Vitali Prakapenka, Jolanta Sztuk-Dambietz, Minxue Tang, Tianqi Xie, Zena Younes, Ulf Zastrau, Alexander F Goncharov, Clemens Prescher, Ryan S McWilliams, Guillaume Morard, Sebastien Merkel
The crystallographic structure of iron under extreme conditions is a key benchmark for cutting-edge experimental and numerical methods. Moreover, it plays a crucial role in understanding planetary cores, as it significantly influences the interpretation of observational data and, consequently, insights into their internal structure and dynamics. However, even the structure of pure solid iron under the Earth’s core conditions remains uncertain, with the commonly expected hexagonal close-packed structure energetically competitive with various cubic lattices. In this study, iron was compressed in a diamond anvil cell to above 200 GPa, and dynamically probed near the melting point using MHz frequency X-ray pulses from the European X-ray Free Electron Laser. The emergence of an additional diffraction line at high temperatures suggests the formation of an entropically stabilized bcc structure. Rapid heating and cooling cycles captured intermediate phases, offering new insights into iron’s phase transformation paths. The appearance of the bcc phase near melting at extreme pressures challenges current understanding of the iron phase diagram under Earth’s core conditions.
Materials Science (cond-mat.mtrl-sci)
Controlling quantum phases with electric fields in one-dimensional Hubbard systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-22 20:00 EDT
D. Arisa, R. M. Dos Santos, Isaac M. Carvalho, Vivian V. França
Quantum systems under electric fields provide a powerful framework for uncovering and controlling novel quantum phases, especially in low-dimensional systems with strong correlations. In this work, we investigate quantum phase transitions induced by an electric potential difference in a one-dimensional half-filled Hubbard chain. By analyzing (i) tunneling and pairing mechanisms, (ii) charge and spin gaps, and (iii) entanglement between the chain halves, we identify three distinct phases: Mott insulator, metal and band-like insulator. The metallic regime, characterized by the closing of both charge and spin gaps, is accompanied by a field-dependent kinetic energy and a quasi-periodic oscillatory behavior of pairing response and entanglement. Although the metallic phase persists for different magnetizations, its extent in the phase diagram shrinks as spin polarization increases.
Strongly Correlated Electrons (cond-mat.str-el)
All-electrical near-field injection of excitons in a van der Waals antiferromagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-22 20:00 EDT
Jonas D. Ziegler, Sotirios Papadopoulos, Antti J. Moilanen, Marcelo M. Valenzuela, Qia Lin, Kseniia Mosina, Takashi Taniguchi, Kenji Watanabe, Zdenek Sofer, Florian Dirnberger, Lukas Novotny
Van der Waals materials have become a promising building block for future electronics and photonics. The two-dimensional magnet CrSBr came into the spotlight of solid state research due to its intriguing combination of antiferromagnetic order, strong light-matter coupling and unusual quasi-1D electronic bandstructure. This study reports the electrical excitation of excitons in CrSBr layers from cryogenic temperatures up to room temperature. By exploiting the energy transfer via tunneling electrons in a graphene tunnel junction strongly bound excitons are excited in proximate CrSBr layers. This facilitates electrically-excited emission from CrSBr crystals ranging in thickness from a bilayer up to 250 nm, in which the strong linear polarization of the electroluminescence confirms the excitonic origin. For thicker layers, clear evidence for the electrically excited emission from self-hybridized exciton polaritons is observed, highlighting the strong coupling between optical excitations and confined photon modes in CrSBr. These results pave the way for future applications in spintronic and optical readout of magnetic properties.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Entropy exchange in an inter-correlating binary quasi-classical system: Concept of entropy-bath accelerated molecular dynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-22 20:00 EDT
This letter highlights the entropy exchange phenomenon in a coupled binary inter-correlating system following Haldane’s non-linear statistical correlation. A unique coupling between a classical and a quantum-like system at the marginal distribution is observed. It is shown that the quantum nature of a system can arise without any self-correlation. Extending this idea, an enhanced sampling method in molecular dynamics simulation is postulated where a classical system is forced to show quantum-like behavior with the help of an entropy-bath. An entropy-bath exchanges entropy with the system to scale the potential energy distribution of the system, so that a probability upper bound at each energy level is maintained. An algorithm to implement the entropy-bath accelerated molecular dynamics simulation is discussed. Using low temperature vitreous silica as an example, the capability of such an algorithm to greatly improve sampling of the potential energy landscape under equilibrium conditions for kinetically arrested systems is highlighted.
Statistical Mechanics (cond-mat.stat-mech)
6 pages, 2 figures
Chemical design of monolayer altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Runzhang Xu, Yifan Gao, Junwei Liu
The crystal-symmetry-paired spin-momentum locking (CSML) arisen from the intrinsic crystal symmetry connecting different magnetic sublattices in altermagnets enables many exotic spintronics properties such as unconventional piezomagnetism and noncollinear spin current. However, the shortage of monolayer altermagnets restricts further exploration of dimensionally confined phenomena and applications of nanostructured devices. Here, we propose general chemical design principles inspired by sublattice symmetry of layered altermagnet V$ _2$ (Se,Te)$ _2$ O through symmetry-preserving structural modification and valence-adaptive chemical substitutions. In total, we construct 2600 candidates across four structural frameworks, M$ _2$ A$ _2$ B$ _{1,0}$ and their Janus derivatives. High-throughput calculations identify 670 potential altermagnets with Néel-ordered ground states, among which 91 ones exhibiting CSML Dirac cones that enable spin-polarized ultra-fast transport. These materials also feature different ground-state magnetic orderings and demonstrate diverse electronic behaviors, ranging from semiconductors, metals, half-metals, to Dirac semimetals. This work not only reveals abundant monolayer altermagnets, but also establishes a rational principle for their design, opening gates for exploration of confined magnetism and spintronics in atomically thin systems.
Materials Science (cond-mat.mtrl-sci)
11 pages, 5 figures
Eu-doped CsSrCl$_3$ Large Nanocrystal Clusters with Self-Reduction Effect and Near-Unity Quantum Yield
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Chuangchang Lei, Xiang Wu, Yaohua Li, Xu Xu, Guangzheng Zuo, Qiongrong Ou, Shuyu Zhang
Europium halide perovskites have emerged as promising candidates for environmental-friendly blue-emitting materials. However, their development is hindered by relative low photoluminescence quantum yields (PLQY, e.g. ~2-5% for intrinsic CsEuCl3) and poor stability against air. Here, we introduce a one-step-procedure for synthesizing Eu$ ^{2+}$ -doped CsSrCl$ _3$ large nanocrystal clusters (LNCs) with the effect of self-reduction, therefore eliminating the use of conventional reductant oleylamine (OAm) and ensuring phase purity. The CsSrCl$ _3$ :Eu LNCs shows photoluminescence emission centered at 430 nm with a full width at half-maximum (FWHM) of 25 nm and a PLQY of ~40%, which can be further enhanced to ~97% after passivating the surface defects by adding trioctylphosphine (TOP), the highest among all reported lead-free blue-emitting perovskite nanocrystals. The stability of CsSrCl$ _3$ :Eu can also be improved significantly by epitaxially growing ZnS shell on the surface. This work will shed more light on lanthanide and alkaline-earth metal (AEM)-based perovskites for nontoxic light-emitting materials.
Materials Science (cond-mat.mtrl-sci)
Mott transition and correlation effects on strictly localized states in an octagonal quasicrystal
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-22 20:00 EDT
Efe Yelesti, Onur Erten, M. O. Oktel
Flat-band systems have attracted significant attention as platforms for studying strongly correlated electron physics, where the dominance of electron-electron interactions over kinetic energy gives rise to a variety of emergent phenomena. Quasicrystals are compelling systems for studying these phenomena as they host degenerate strictly localized states at zero energy due to perfect destructive interference patterns. In this study, we use the slave-rotor mean-field approach to investigate the effects of electron interactions within the Hubbard model on the Ammann-Beenker quasicrystal. The phase diagram characterizing metallic and Mott insulator regions indicates a first-order phase transition. Our analysis shows that the local coordination number affects the local quasiparticle weight, displaying varying metallicity across the sites. Furthermore, we focus on the strictly localized states that arise in the non-interacting limit. We find that interactions and deviation from particle-hole symmetry induce spectral splitting, broadening, and partial delocalization of the localized states, depending on the local environment. In particular, certain localized states with higher coordination numbers remain more robust compared to others. Our results highlight the critical role of local geometry in shaping correlation effects in flat-band quasicrystals.
Strongly Correlated Electrons (cond-mat.str-el), Disordered Systems and Neural Networks (cond-mat.dis-nn)
11 pages, 8 figures
First-principles calculations of transport coefficients in Weyl semimetal TaAs
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Guillaume E. Allemand, Matteo Giantomassi, Matthieu J. Verstraete
We study charge and heat transport from first-principles in the topological Weyl semimetal TaAs. Electron-phonon coupling matrix elements are calculated using density functional perturbation theory and used to derive the thermo-electric transport coefficients, including the electrical conductivity, Seebeck coefficient, electronic thermal conductivity and the Peltier coefficient. We compare the self-energy and momentum relaxation time approximations to the iterative solution of the Boltzmann Transport Equation, finding they give similar results for TaAs provided the chemical potential is treated accurately. For the iterative method, we derive an additional equation, which is needed to fully solve for transport under both thermal and an electrical potential gradients. Interestingly, the Onsager reciprocity between $ S$ and $ \Pi$ is no longer imposed, and we can deal with systems breaking time-reversal symmetry, in particular magnetic materials. We compare our results with the available experimental data for TaAs: the agreement is excellent for $ \sigma_{xx}$ , while $ \sigma_{zz}$ is overestimated, probably due to differences in experimental carrier concentrations. The Seebeck coefficient is of the same order of magnitude in theory and experiments, and we find that its low-T behavior also strongly depends on the doping level.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Exciton-defect interaction and optical properties from a first-principles T-matrix approach
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Yang-hao Chan, Jonah B. Haber, Mit H. Naik, Diana Y. Qiu, Felipe H. da Jornada
Understanding exciton-defect interactions is critical for optimizing optoelectronic and quantum information applications in many materials. However, ab initio simulations of material properties with defects are often limited to high defect density. Here, we study effects of exciton-defect interactions on optical absorption and photoluminescence spectra in monolayer MoS2 using a first-principles T-matrix approach. We demonstrate that exciton-defect bound states can be captured by the disorder-averaged Green’s function with the T-matrix approximation and further analyze their optical properties. Our approach yields photoluminescence spectra in good agreement with experiments and provides a new, computationally efficient framework for simulating optical properties of disordered 2D materials from first-principles.
Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
Tailoring the Electronic Configurations of YPc$_2$ on Cu(111): Decoupling Strategies for Molecular Spin Qubits Platforms
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-22 20:00 EDT
Soyoung Oh, Franklin. H. Cho, We-hyo Soe, Jisoo Yu, Hong Bui, Lukas Spree, Caroline Hommel, Wonjun Jang, Soo-hyon Phark, Luciano Colazzo, Christoph Wolf, Fabio Donati
Among molecular spin qubit candidates, yttrium phthalocyanine double-decker (YPc$ _2$ ) features a diamagnetic metal ion core that stabilizes the molecular structure, while its magnetic properties arise primarily from an unpaired electron (S = 1/2) delocalized over the phthalocyanine (Pc) ligand. Understanding its properties in the proximity of metal electrodes is crucial to assess its potential use in molecular spin qubits architectures. Here, we investigated the morphology and electronic structure of this molecule adsorbed on a metal Cu(111) surface using scanning tunneling microscopy. On that surface, YPc$ _2$ adsorbs flat, with isolated molecules showing a preferred orientation along the (111) crystal axes. We observed two different types of self-assembly molecular packing when growing the molecular patches on Cu(111). For YPc$ _2$ in direct contact with Cu(111), scanning tunneling spectroscopy revealed a widely separated highest occupied (HOMO) and lowest unoccupied molecular orbitals (LUMO), suggesting the quenching of the unpaired spin. Conversely, when the YPc$ _2$ is separated from the substrate by a few-layer thick diamagnetic ZnPc layer, we find the HOMO to split into singly occupied (SOMO) and singly unoccupied molecular orbitals (SUMO). We find that more than 2 layers of ZnPc are needed to avoid intermixing between the two molecules and spin quenching in the YPc$ _2$ . Density functional theory reveals the spin quenching to be due to the hybridization between YPc$ _2$ and Cu(111) states, confirming the importance of using suitable decoupling layers to preserve the unpaired molecular spin. Our results suggest the potential of YPc$ _2$ /ZnPc heterostructures as a stable and effective molecular spin qubit platform and validates the possibility of integrating this molecular spin qubit candidate in future quantum logic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chemical Physics (physics.chem-ph)
Exciton Bohr radius of lead halide perovskites for photovoltaic and light-emitting applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Hyun Myung Jang, Kyung Yeon Jang, Song Hee Lee, Jinwoo Park, Tae-Woo Lee
Exciton Bohr radius (a_B) and exciton binding energy (E_b) of metal halide perovskites are two prime quantities in their applications to both light-emitting diode displays and photovoltaic devices. We develop a reliable theoretical method of simultaneously finding a_B and {\epsilon}_r^c (dielectric constant) based on the net exciton energy above the bulk band gap. It is estimated that a_B under the dielectric confinement is substantially smaller than a_B in the absence of dielectric confinement: 4.36 nm vs. 5.61 nm in the case of CH3NH3PbBr3. We attribute the enhanced a_B to variations of {\epsilon}_r^c and the electron-hole correlation energy. We also develop a simple method of finding E_b based on the same net exciton energy. Using this, we attribute the well-known difference in E_b between organic bromide perovskites and iodide counterparts to {\epsilon}_r^c and explain that iodide perovskites are more suited than bromide counterparts in photovoltaic applications, which require smaller E_b for efficient charge-carriers transport.
Materials Science (cond-mat.mtrl-sci)
38 pages including Supplementary Materials, 5 figures, 2 tables, 23 equations (Main Manuscript), 41 references
Triplet Excitons Reconcile Charge Generation and Recombination in Low-Offset Organic Solar Cells: Efficiency Limits from a 5-State Model
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Jonathan L. Langentepe-Kong, Manasi Pranav, Safa Shoaee, Dieter Neher
The power conversion efficiency of organic solar cells has recently improved beyond 20%. The active layers of these devices comprise of at least two organic semiconductors, forming a type II heterojunction. Hereby, the device performance is determined by the kinetic interplay of various species, including localized excitons, charge transfer state as well as charge-separated states. However, a model which describes all relevant photovoltaic measures has yet to be developed. Herein, we present a comprehensive 5-state rate model which includes both singlet and triplet charge transfer states and takes into account the formation, re-splitting and decay of the local triplet state, parametric in the respective energy offset. We show that this model not only describes key device properties such as charge generation efficiency, photoluminescence, electroluminescence and Langevin reduction factor simultaneously but also elucidate how these vary across material combinations based on the D:A interfacial energy offset alone. We find that the electroluminescence and Langevin reduction factor depend strongly on the triplet properties and that the triplet decay becomes the dominant charge recombination pathway for systems with moderate offset, in full agreement to previous experimental results. Validation against literature data demonstrates the model’s ability to predict the device efficiency accurately. Subsequently, we identify material combinations with singlet exciton to charge transfer state energetic offset of roughly 150meV as particularly promising. Our model explains further why recent certified efficiency records for binary blends remain at ca. 20% if no further means to improve photon and charge carrier harvesting are taken.
Materials Science (cond-mat.mtrl-sci)
main text: 14 pages (with references) and 7 figures, total: 32 pages (with SI) and 17 figures. To be submitted within the next few days
Entanglement of Inhomogeneous Free Bosons and Orthogonal Polynomials
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-22 20:00 EDT
Pierre-Antoine Bernard, Rafael I. Nepomechie, Gilles Parez, Eric Ragoucy, David Raveh, Luc Vinet
In this paper, we investigate the ground-state entanglement entropy in inhomogeneous free-boson models in one spatial dimension. We develop a powerful method to extract the leading term in the entanglement scaling, based on the analytic properties of the inhomogeneous potential. This method is applicable to a broad class of models with smooth spatial inhomogeneities. As a case study, we apply this approach for a family of exactly-solvable models characterized by orthogonal polynomials of the Askey scheme, finding a perfect match between the numerical and analytical results.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
14 pages, 7 figures
Congestion and extreme events in urban street networks
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-22 20:00 EDT
Congestion and extreme events in transportation networks are emergent phenomena with significant socio-economic implications. In this work, we study congestion and extreme event properties on real urban street (planar) networks drawn from four cities and compare it with that on a regular square grid. For dynamics, we employ three variants of random walk with additional realistic transport features. In all the four urban street networks and 2D square grid and with all dynamical models, phase transitions are observed from a free flow to congested phase as a function of birth rate of vehicles. These transitions can be modified by traffic-aware routing protocols, but congestion cannot be entirely mitigated. In organically evolved street networks, we observe a semi-congested regime which has both congested and free-flow components. In the free-flow regime, the extreme event occurrence probability is larger for small degree nodes than for hubs, a feature originally observed in non-planar scale-free networks. In general, with respect to congestion and extreme events, the urban street networks and regular square grid display similar properties.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Data Analysis, Statistics and Probability (physics.data-an)
8 pages, 9 figures
Lithium Intercalation in the Anisotropic van der Waals Magnetic Semiconductor CrSBr
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Kseniia Mosina (1), Aljoscha Söll (1), Jiri Sturala (1), Martin Veselý (2), Petr Levinský (3), Florian Dirnberger (4), Giuliana Materzanini (5), Nicola Marzari (6), Gian-Marco Rignanese (5 and 7), Borna Radatović (1), David Sedmidubsky (1), Zdeněk Sofer (1) ((1) Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Czech Republic, (2) Department of Organic Technology, University of Chemistry and Technology Prague, Czech Republic, (3) Institute of Physics of the Czech Academy of Sciences, Czech Republic, (4) Department of Physics, TUM School of Natural Sciences, Technical University of Munich, Germany, (5) Institute of Condensed Matter and Nanosciences (IMCN), Université catholique de Louvain, Belgium, (6) Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne (EPFL), Switzerland, (7) Wel Research Institute, Belgium)
Alkali metal intercalation is an important strategy for doping van der Waals materials. Lithium, in particular, was shown to achieve exceptional charge carrier densities, reaching levels at which fundamental electrical, optical, and magnetic material properties begin to be strongly modified. While lithium is known to be highly volatile, its migration dynamics in anisotropic layered crystals remain poorly understood. In this work, we investigate the intercalation of lithium in-between layers of the anisotropic magnetic semiconductor CrSBr. Using exfoliated crystals, we are able to monitor the dynamics of the intercalation process in real time through optical and electrical characterization methods. Our measurements reveal highly anisotropic migration of Lithium characterized by diffusion coefficients that differ by more than one order of magnitude along a- and b-directions. This finding is in good agreement with our molecular dynamics simulations which show trajectories of lithium atoms primarily follow the Br-chains in the a-direction. Beyond that, we find that partially covering CrSBr crystals by thin hexagonal boron nitride (hBN) flakes has a significant impact on the intercalation process, and that lithium strongly enhances the electrical conductivity along the a-axis. Our method offers a new platform for lithium diffusion studies and encourages further research to pursue the fabrication of lithium-doped devices.
Materials Science (cond-mat.mtrl-sci)
Shubnikov-de Haas Oscillations in 2D $\text{PtSe}_2$: A fermiological Charge Carrier Investigation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-22 20:00 EDT
Julian Max Salchegger, Rajdeep Adhikari, Bogdan Faina, Alberta Bonanni
High magnetic field and low temperature transport is carried out in order to characterize the charge carriers of $ \text{PtSe}_2$ . In particular, the Shubnikov-de Haas oscillations arising at applied magnetic field strengths $ \gtrsim 4.5,\text{T}$ are found to occur exclusively in plane and emerge at a layer thickness of $ \approx 18,\text{nm}$ , increasing in amplitude and decreasing in frequency for thinner $ \text{PtSe}_2$ flakes. Moreover, the quantum transport time, Berry phase, Dingle temperature and cyclotron mass of the charge carriers are ascertained. The emergence of weak antilocalization (WAL) lies in contrast to the presence of magnetic moments from Pt vacancies. An explanation is provided on how WAL and the Kondo effect can be observed within the same material. Detailed information about the charge carriers and transport phenomena in $ \text{PtSe}_2$ is obtained, which is relevant for the design of prospective spintronic and orbitronic devices and for the realization of orbital Hall effect-based architectures.
Materials Science (cond-mat.mtrl-sci)
12 pages, 15 figures
Coupling quantum spin ice to matter on the centered pyrochlore lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-22 20:00 EDT
Rajah P. Nutakki, Sylvain Capponi, Ludovic D. C. Jaubert, Lode Pollet
The low-energy physics of quantum spin ice is known to support an emergent form of quantum electrodynamics (QED), where magnetic monopoles exist and the fine structure constant is material dependent. In this article, we show how this QED is modified via a coupling to dynamical matter on the centered pyrochlore lattice, a structure which has recently been synthesized using metal-organic frameworks. Specifically, we study the low-energy properties of the S = 1/2 quantum XXZ model on the centered pyrochlore lattice. At fourth order in degenerate perturbation theory, this model hosts a quantum spin liquid distinct from the well-known U(1) quantum spin ice on the pyrochlore due to the presence of dynamical matter in the ground state. Exact diagonalization results are consistent with this quantum spin liquid over an extended region of the ground state phase diagram although potential quantum critical points within this region could indicate a richer phase structure. Our work thus expands the physics of quantum spin ice in an experimentally motivated geometry, providing the framework for understanding how the emergent QED behaves in the presence of dynamical matter.
Strongly Correlated Electrons (cond-mat.str-el)
21 pages, 20 figures
Splay Stiffening and Twist Softening in a Ferroelectric Nematic Liquid Crystal
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-22 20:00 EDT
Evangelia E. Zavvou, Alexander Jarosik, Hajnalka Nádasi, Christoforos A. Krontiras, Panagiota K. Karahaliou, Rachel Tuffin, Melanie Klasen-Memmer, Alexey Eremin
The recent discovery of ferroelectric nematics-genuine 3D ferroelectric fluids-has underscored the importance of electrostatic interactions in shaping the physical behaviour of soft matter systems. In this paper, we investigate the mechanical properties of ferroelectric nematics by directly comparing the splay and twist elastic constants in a liquid crystal system that exhibits both nonpolar and ferroelectric nematic phases. Our results reveal that polar ordering results in increased splay rigidity and a concomitant reduction in twist elasticity.
Soft Condensed Matter (cond-mat.soft)
Linear scaling relation between two-dimensional massless Dirac fermion Fermi velocity and Fe-As bond length in iron arsenide superconductor systems
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-22 20:00 EDT
Chengpu Lv, Jianzhou Zhao, Yueshan Xu, Yu Song, Chenglin Zhang, Mykhaylo Ozerov, Pengcheng Dai, Nan-Lin Wang, Zhi-Guo Chen
Two-dimensional (2D) massless Dirac fermions (MDF), which represent a type of quasi-particles with linear energy-momentum dispersions only in 2D momentum space, provide a fertile ground for realizing novel quantum phenomena. However, 2D MDF were seldom observed in the superconducting bulk states of 3D materials. Furthermore, as a cornerstone for accurately tuning the quantum phenomena based on 2D MDF, a quantitative relationship between 2D MDF and a structural parameter has rarely been revealed so far. Here, we report magneto-infrared spectroscopy studies of the iron-arsenide-superconductor systems NaFeAs and $ A\mathrm{Fe_2As_2} (A = \mathrm{Ca, Ba})$ at temperature $ T \sim 4.2 $ K and at magnetic fields ($ B$ ) up to 17.5 T. Our results demonstrate the existence of 2D MDF in the superconducting bulk state of NaFeAs. Moreover, the 2D-MDF Fermi velocities in NaFeAs and $ A\mathrm{Fe_2As_2} (A = \mathrm{Ca, Ba})$ , which are extracted from the slopes of the linear $ \sqrt{B}$ dependences of the Landau-level transition energies, scale linearly with the Fe-As bond lengths. The linear scaling between the 2D-MDF Fermi velocities and the Fe-As bond lengths is supported by (i) the linear relationship between the square root of the effective mass of the $ d_{xy}$ electrons and the Fe-As bond length and (ii) the linear dependence of the square root of the calculated tight-binding hopping energy on the Fe-As bond length. Our results open up new avenues for exploring and tuning novel quantum phenomena based on 2D MDF in the superconducting bulk states of 3D materials.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Accepted in Physical Review B (Letter)
Majorana Zero Modes in a Heterogenous Structure of Topological and Trivial Domains in FeSe$_{1-x}$Te$_x$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-22 20:00 EDT
Prashant Gupta, Jasmin Bedow, Eric Mascot, Dirk K. Morr
We propose that the existence of vortices in FeSe$ _{1-x}$ Te$ _x$ with and without Majoarana zero modes (MZMs) can be explained by a heterogeneous mixture of strong topological and trivial superconducting domains, with only vortices in the former exhibiting MZMs. We identify the spectroscopic signatures of topological and trivial vortices and show that they are necessarily separated by a domain wall harboring Majorana edge modes. We demonstrate that when a vortex is moved from a trivial to a topological domain in real time, a domain wall Majorana edge mode is transferred to the vortex as an MZM.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Supplementary Movie available upon request