Strongly Correlated Electrons · Cross-listed from cond-mat.mtrl-sci
Nanoscale Sr$_2$IrO$_4$ Freestanding Thin-Films for Flexible Electronics
Sujan Shrestha, Matthew Coile, Menglin Zhu et al. (+7 more)
We report the structural and optical properties of nanoscale Sr2IrO4 freestanding thin-films fabricated using a water-soluble Sr3Al2O6 layer. The coherent
lattice structure,
phonon modes, two-
magnon Raman scattering, and optical absorption spectra of the Sr2IrO4 nanomembrane are analogous to those of the layered iridate epitaxial thin-films and single
crystals. Remarkably, the formation of 3-unit-
cell-thick SrIrO3 and interfacial composite layers alleviates antiphase boundaries at the Sr2IrO4/Sr3Al2O6 interface, resulting in structurally-robust nanomembranes. Our experimental results show that this freestanding thin-film approach of layered oxides can provide techniques for tuning or realizing unprecedented states beyond conventional thin-film methods, suggesting a pathway in achieving flexible layered-oxide electronics.
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All authors Sujan Shrestha, Matthew Coile, Menglin Zhu, Maryam Souri, Jiwoong Kim, Rina Pandey, Joseph Brill, Jinwoo Hwang, Jong-Woo Kim, Ambrose Seo
Strongly Correlated Electrons
Thermally melted quadrupolar order and intrinsically quantum phases in 5$d^1$ double perovskites
Rong Cong, Ginevra Corsale, Ilija K. Nikolov et al. (+3 more)
Spin-orbit-coupled $d^1$ double perovskites exhibit a rich interplay of
spin, orbital, and quadrupolar degrees of freedom (DOF), giving rise to competing
magnetic and multipolar phases. Although
quantum mean-field theories predict many exotic phases, their stability against thermal fluctuations and reproducibility within a classical framework remain an open question. Here, we surpass the mean-field limitations by deploying large-scale classical Monte Carlo simulations on the projected $j=3/2$
manifold of the FCC
lattice, allowing complex ordering patterns to emerge spontaneously without preassigned
magnetic symmetries. Our thermodynamic mapping reveals that thermal fluctuations melt the intermediate-temperature quadrupolar phase over part of the phase diagram, while it survives intact elsewhere. Crucially, by systematically isolating the boundary between classical and
quantum stability, we demonstrate that while the four-sublattice antiferromagnetic and ferromagnetic (FM) phases are robustly classical, the coplanar canted FM[110] state completely destabilizes. This identifies the FM[110] phase as an intrinsically
quantum state born out of
quantum fluctuations. Our results demonstrate that the dominant
magnetic phases are robust within a classical description, where the essential physics of the system is captured by weakly entangled, short-range correlated DOF and highlight the role of thermal fluctuations in determining the stability of different types of
magnetic and quadrupolar order.
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All authors Rong Cong, Ginevra Corsale, Ilija K. Nikolov, Wenjuan Zhang, Nandini Trivedi, Vesna F. Mitrović
Strongly Correlated Electrons · Cross-listed from hep-th
Anyon Crystallization by Statistics
Zohar Komargodski, Xuzixiang Lou, Ivri Nagar et al. (+3 more)
We revisit the long-standing problem of the anyon gas. We study the solvable near-bosonic limit of a large number of anyons $N$ at fixed $N/k$, where $1/k$ characterizes the statistical interaction. In this limit, the ground state is a
crystal with order $N/k$
lattice sites. The statistical interactions, mediated by a long-range gauge field, are completely screened within the crystalline phase. The resulting state is a conventional
crystal without superfluidity. We characterize this anyon
crystal by determining its unit-
cell size, ground-state energy, acoustic excitations, angular momentum crossings, and other properties. Our results indicate a
quantum phase transition between the
crystal at $k>k_c$ and a superfluid at $k<k_c$, with a critical value $k_c\simeq2\text{--}5$. These results imply that an anyon gas with only statistical interactions is not necessarily a superfluid, contrary to common lore. We also present a detailed analysis of the renormalization-group
evolution of anyon–anyon interactions, identifying many new potential fixed points and elucidating finite-size effects.
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All authors Zohar Komargodski, Xuzixiang Lou, Ivri Nagar, Domenico Orlando, Susanne Reffert, Amit Sever
Strongly Correlated Electrons
Extended symmetric quantum phase in a honeycomb Heisenberg model with sublattice-selective interactions
Nai Chao Hu, Xing-Yu Zhang, Yuchi He et al. (+1 more)
Motivated by two-dimensional bilayer systems we numerically study an anti-ferromagnetic
spin-$1/2$ Heisenberg model on the honeycomb
lattice with a nearest-neighbour exchange coupling $J_1$, and a next-nearest-neighbour exchange coupling $J_2'$ for the B sublattice sites only. Using infinite Projected Entangled-Pair States (iPEPS), variational uniform
matrix-product states on cylinders, and exact diagonalization, we find an extended symmetric regime $0.4\lesssim J'_2/J_1\lesssim0.6$, in which local observables show no
magnetic, valence-bond, or chiral
spin order. At $J'_2/J_1=0.5$, the PEPS correlation length grows systematically with bond dimension, and an inverse-correlation-length extrapolation favors a vanishing limit. We also find that various observables scale algebraically with the finite bond-dimension-induced correlation length, which points to a gapless
spin liquid ground state. We propose a $\mathbb{Z}_2$ Dirac
spin liquid parton state, with Dirac points that are protected by translation, time-reversal and three-fold rotation
symmetry, as a promising candidate state to explain the numerical results. We also discuss the possibility that the symmetric ground state is a featureless, short-range entangled state with a small gap.
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All authors Nai Chao Hu, Xing-Yu Zhang, Yuchi He, Nick Bultinck
Strongly Correlated Electrons
From Effective Temperature to Non-Boltzmann State Selection in Driven-Dissipative Quantum Criticality
Tiago Jorge, Jens Paaske and Pedro Ribeiro
Whether a nonequilibrium
quantum-critical steady state can be described by an effective temperature remains an open question. We address it in a voltage-biased electronic Lipkin–Meshkov–Glick model, a minimal driven-dissipative model of a collective
spin coupled to metallic leads. A controlled large-$N$ treatment reveals an overdamped open
quantum-critical regime distinct from the closed model. The surrounding
quantum critical fan, organized by temperature and voltage, is explored and fluctuations are found to be governed by an effective temperature $T_{\rm eff}$. At strong bias, the transition becomes first-order through a tricritical point. Remarkably, the same $T_{\rm eff}$ governs the strongly driven regime, but now varies across the entire order-parameter landscape. The steady state is therefore selected by a non-Boltzmann rule, shifting the first-order transition away from the equal-depth point of a deterministic potential. Driven criticality thus remains organized by an effective temperature while revealing non-thermal state selection.
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Strongly Correlated Electrons
Kitaev spin liquid in superconducting networks
Guilherme Delfino, Mehmet Dede, Dmitry Green et al. (+3 more)
We propose a realization of the Kitaev honeycomb
Hamiltonian – an archetypal
spin-
liquid model – in a superconducting metamaterial. The architecture consists of Cooper-pair boxes coupled through depleted
semiconductor–
superconductor heterostructures that do not require
spin–orbit coupling. The Cooper-pair boxes encode effective
spin degrees of freedom, while normal and anomalous virtual propagation through the
heterostructures mediate bond-directional interactions. Two key control parameters are an out-of-plane
magnetic flux and the
semiconductor Fermi energy. The former controls interference and distinguishes the bond directions, while tuning the latter close to the bottom of the band gives rise to an emergent Nambu-exchange
symmetry that enforces the required bond directionality. Through numerical calculations, we identify an operating regime with controlled corrections, with associated energy and length scales within experimental reach. These results establish a route toward
equilibrium quantum spin liquids in engineered superconducting networks.
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All authors Guilherme Delfino, Mehmet Dede, Dmitry Green, Michael J. Manfra, Charles M. Marcus, Claudio Chamon
Strongly Correlated Electrons
Re-entrant p-wave superconductivity in a Chern Dartboard Insulator
Yueyang Wu, Rebecca Chan, Taylor L. Hughes et al. (+1 more)
We formulate an exact theory for a 2-band
superconductor with inter-orbital pairing and band Hatsugai-Kohmoto (HK) interactions. We apply this theory to a Chern dartboard
insulator and compute the pair susceptibility and pair correlations analytically. We find that in the insulating phase previously predicted by BCS theory (small pairing strength $g$, chemical potential $\mu$ in the gap), the HK interaction can induce superconductivity, and possibly a Chern dartboard
superconductor, by lifting the doubly-occupied band and making it cross the chemical potential. From this HK-induced
superconductor, we notice that in a significant parameter range (HK interaction strength $U = 1$, $\mu = 0.5$), an
insulator-
superconductor-
insulator re-entrant transition exists. We isolate the re-entrance to a conflation between HK interactions and inter-orbital pairings.
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All authors Yueyang Wu, Rebecca Chan, Taylor L. Hughes, Philip W. Phillips
Strongly Correlated Electrons · Cross-listed from quant-ph
Lukas Homeier, Simon Linsel, Lode Pollet et al. (+1 more)
Quantum simulators are beginning to prepare long-sought phases of matter that remain difficult to realize cleanly in materials. Yet identifying such phases remains a major challenge when their defining properties are inherently non-local and cannot be captured by conventional local measurements. Here we establish multiple-
quantum coherences (MQCs) as phase-sensitive diagnostics for gapped $\mathbb{Z}_2$
quantum spin liquids. Focusing on the extended toric code and using large-scale
quantum Monte Carlo simulations, we build a direct correspondence between the elementary anyonic excitations and the weights of different MQC sectors. MQCs thereby reveal anyon condensation across the phase transitions through characteristic signatures that remain robust against fluctuations that obscure conventional diagnostics. Subsystem-resolved MQCs further provide a bipartite
entanglement witness that distinguishes a classical loop gas from a
quantum-coherent closed-loops gas. We develop and
benchmark a practical protocol to extract MQCs based on the return fidelity of adiabatic round trips, and show that local coherence measurements retain experimentally accessible signatures of the phase transitions. Our results establish MQCs as a practical diagnostic for the excitations, phase structure and global constraints of
quantum spin liquids.
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All authors Lukas Homeier, Simon Linsel, Lode Pollet, Ana Maria Rey
Strongly Correlated Electrons
Staged emergence of anomalous Hall transport in a correlated uranium Weyl semimetal
Sabin Regmi, Shuxiang Zhou, Chandan K. Singh et al. (+9 more)
Understanding how electronic correlations reshape topological states remains a central challenge in
quantum materials. Here we investigate the uranium ferromagnet UPS using magnetotransport, angle-resolved photoemission spectroscopy, thermodynamic measurements, and first principles calculations. Resonant photoemission reveals narrow U-$5f$ spectral weight at the Fermi level coexisting with broad incoherent states, consistent with the itinerant/localized duality characteristic of uranium $5f$ electrons. The anomalous Hall conductivity reaches approximately $4.5\times10^{2}\,\Omega^{-1}\mathrm{cm}^{-1}$, yet does not simply follow the ordered
magnetic moment. Temperature dependent photoemission reveals relatively little change across $T_C=118$~K, followed by a pronounced redistribution of low-energy $5f$ spectral weight below approximately 90~K. First-principles calculations identify a
symmetry protected Weyl crossing with pronounced Berry
curvature and yield an intrinsic anomalous Hall conductivity of approximately $9.6\times10^{2}\,\Omega^{-1}\mathrm{cm}^{-1}$. These results demonstrate that
magnetic order, correlated electronic reconstruction, and anomalous Hall transport develop over distinct but overlapping temperature ranges, revealing how strong correlations reshape topological transport in a uranium Weyl semimetal.
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All authors Sabin Regmi, Shuxiang Zhou, Chandan K. Singh, Alexei Fedorov, Jonathan Denlinger, Zeyu Ma, Yidi Wang, Jennifer E. Hoffman, Peter M. Oppeneer, Dariusz Kaczorowski, Tomasz Durakiewicz, Krzysztof Gofryk
Strongly Correlated Electrons
Quantum-interference-driven orbital density wave and high-temperature superconductivity in trilayer nickelates
Youichi Yamakawa and Hiroshi Kontani
Intertwined charge-density-wave (CDW) and
spin-density-wave (SDW) orders are a hallmark of high-temperature superconducting multilayer nickelates. In trilayer La4Ni3O_{10}, charge correlations develop at temperatures above the onset of long-range
spin order, and the characteristic ordering wavevectors satisfy $Q_{cdw} \approx 2Q_{sdw}$. Here, using a density-wave equation with vertex corrections, we show that
quantum interference between short-range SDW fluctuations at $q \approx Q_{sdw}$ on the outer NiO2 layers generates an inter-outer-layer bond order at $Q_{cdw} \approx 2 Q_{sdw}$. This bond order induces a pronounced inner-layer-centered orbital order, with antiphase modulations of the Ni $d_{3z^2-r^2}$ and $d_{x^2-y^2}$ occupations, producing strong orbital polarization but only weak total charge modulation. This intertwined bond-and-orbital order accounts for the layer-selective electronic reconstruction inferred from NMR/NQR and is consistent with Raman spectroscopy and scanning tunnelling microscopy measurements. The same orbital and
spin fluctuations also cooperate to stabilize $s_{\pm}$-wave superconductivity through $M_z$ mirror-parity selection rules. Our results provide a unified microscopic framework for intertwined density-wave order and high-Tc superconductivity in multilayer nickelates.
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Strongly Correlated Electrons
Anisotropic Surface State Band Splitting and Low Energy Flat Bands in 3d Correlated Topological Kondo Insulator Candidate FeSb$_2$
Ziling Cao, Jie Pang, Yu Xu et al. (+22 more)
FeSb$_2$ is a correlated narrow-gap
semiconductor that has often been discussed as a $3d$-electron Kondo
insulator candidate and exhibits a low-temperature resistance plateau with possible surface-dominated conduction. We carried out a systematic high-resolution
laser-based angle-resolved photoemission spectroscopy (ARPES) study of FeSb$_2$ to investigate its electronic structure. The surface states around the zone center show clear anisotropic splitting. When the temperature is lowered into the resistance plateau regime ($<6\,\mathrm{K}$), the surface states remain robust, but their photoemission peaks become much sharper and gain spectral weight. Two distinct flat-band-like features are observed at low energy. One is located at $\sim$127 meV below the Fermi level, which exists only along a specific high-
symmetry direction, while the other is located at $\sim$70 meV below the Fermi level and is present along all the measured momentum cuts around the zone center. These results provide new information to understand the renormalization effects, the resistance plateau, and the topological nature of FeSb$_2$.
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All authors Ziling Cao, Jie Pang, Yu Xu, Taimin Miao, Bo Liang, Wenpei Zhu, Neng Cai, Mingkai Xu, Jumin Shi, Yingjie Shu, Yiwen Chen, Jiachen Wang, Shenjin Zhang, Fengfeng Zhang, Feng Yang, Zhimin Wang, Qinjun Peng, Zhihai Zhu, Xintong Li, Hanqing Mao, Guodong Liu, Zuyan Xu, Youguo Shi, Lin Zhao, X. J. Zhou
Strongly Correlated Electrons · Cross-listed from cond-mat.supr-con
Electronic Reconstruction Towards Topological Superconductivity in FeTe
Hongtao Rong, Yang Ge, Zi-Jie Yan et al. (+13 more)
The recent discovery of intrinsic superconductivity in stoichiometric FeTe films has renewed interest in the Te-rich end member of the iron chalcogenides for studies of unconventional and topological superconductivity, yet its intrinsic electronic structure remains unresolved. In this work, we combine molecular beam epitaxy, angle-resolved photoemission spectroscopy (ARPES), electrical transport measurements, density functional theory, and embedded dynamical mean-field theory to track the electronic reconstruction of 20-unit-
cell FeTe films as Te annealing progressively removes excess interstitial Fe and drives the system from an antiferromagnetic metal to a
superconductor. We find that this
evolution is accompanied by recovered quasiparticle coherence, reduced electronic correlations, a Lifshitz transition, and a topological phase transition, yielding dxy-dominated hole and electron pockets that favor inter-pocket scattering. In addition, a shallow dxz/dyz-derived hole band located about 2 meV below the Fermi level may provide an incipient-band pairing channel, while scattering between the two electron pockets at M may offer additional pairing channels. High-resolution polarization-dependent
laser ARPES measurements further reveal a topological surface state whose circular dichroism is consistent with the expected orbital-angular-momentum texture of stoichiometric FeTe. These results establish the intrinsic low-energy electronic structure of superconducting FeTe and identify the electronic states most relevant to superconductivity. The coexistence of intrinsic superconductivity and a topological surface state establishes stoichiometric FeTe as a promising platform for exploring topological superconductivity and possible Majorana bound states.
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All authors Hongtao Rong, Yang Ge, Zi-Jie Yan, Haoran Lin, Bing Xia, Xiaoda Liu, Zihao Wang, Pu Xiao, Lok-Kan Lai, Stephen Paplini, Jiatao Song, Jiangang Yang, Peter J. Hirschfeld, Shuolong Yang, Jiabin Yu, Cui-Zu Chang
Strongly Correlated Electrons
Rapidly prototyping kagome flat band physics with acoustic metamaterials
Jiatong Yang, Benjamin H. November, Yiting Huang et al. (+3 more)
Flat bands with vanishing group velocity and quenched kinetic energy provide fertile ground for correlated states and exotic phenomena such as unconventional superconductivity. Yet, engineering and characterizing flat bands in
quantum materials is time-consuming and costly, limiting the exploration of the vast design space of possible flat band systems. Acoustic metamaterials offer an accessible alternative: they can be easily simulated, cheaply fabricated, and quickly measured. Here we present a complete workflow to rapidly prototype flat band systems using acoustic metamaterials. Our design directly implements a tight-binding model using air cavities as
lattice sites connected by channels that control hopping, allowing it to generalize to diverse
lattice geometries. Using the kagome
lattice as a proof-of-concept, we demonstrate excellent agreement between tight-binding theory, finite-element simulations, and experimental measurements. We then design a family of extended kagome
lattices whose added sites cancel successively longer-range hopping, flattening the flat band. With fabrication and measurement requiring hours rather than months and a total cost orders of magnitude lower than
quantum materials, our approach enables rapid iteration through candidate
lattices, facilitating the discovery of new flat band physics in
quantum materials.
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All authors Jiatong Yang, Benjamin H. November, Yiting Huang, S. Minhal Gardezi, Harris Pirie, Jennifer E. Hoffman
Strongly Correlated Electrons
Infrared evidence for strong $C_{3}$ symmetry breaking in 1$T$-TiSe$_{2}$
Esther van Grondelle, Kai Rossnagel, Jasper van Wezel et al. (+1 more)
The interplay between
lattice and electron degrees of freedom gives rise to competing ordered states in
quantum materials, which can lead to a series of subsequent
symmetry breaking transitions. While the differences are often subtle, these phases can be distinguished by their remaining point group
symmetries. Here, we use infrared optical spectroscopy to probe
symmetry breaking at the charge density wave transition of 1$T$-TiSe$_{2}$. We uncover a previously unobserved splitting of a doubly degenerate $E_u$ optical
phonon at $T_{\mathrm{CDW}}\approx$ 190 K that constitutes direct evidence for the breaking of three-fold rotational
symmetry. Our finding rules out proposals where the CDW transition to a low temperature chiral or nematic phase takes place through an intermediary state that preserves three-fold
symmetry. The energy difference between the two former $E_{u}$ partners can only be explained by large $C_{3}$ breaking distortions of the same order of magnitude as previously observed changes in bond lengths, suggesting that $C_{3}$
symmetry breaking plays a dominant role in the CDW transition. The linewidth of the single
phonon mode above $T_{\mathrm{CDW}}$ could be consistent with a fluctuating state where three-fold
symmetry is also broken.
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All authors Esther van Grondelle, Kai Rossnagel, Jasper van Wezel, Erik van Heumen
Strongly Correlated Electrons
Raman Scattering Evidence for Fluctuating Kagome-Plane Moments in $\mathrm{B} \parallel [111]$ in Pr$_2$Zr$_2$O$_7$ pyrochlore
Yuanyuan Xu, Huiyuan Man, Nan Tang et al. (+6 more)
The exotic
magnetic properties of the pyrochlore Pr$_2$Zr$_2$O$_7$ are determined by the coupling of
spin, orbital, and
lattice degrees of freedom. Magnetism in this material originates from the non-Kramers Pr$^{3+}$ ion, and the exotic behavior has been discussed both in the framework of dipole-quadrupole properties of
magnetic moments and disorder splitting the non-Kramers doublet. We use magneto-Raman spectroscopy to probe the
crystal electric field (CEF) excitations of Pr$^{3+}$ in
magnetic fields up to 14 T applied along the [100] and [111] crystallographic directions at 2 K. For $\mathrm{B}\parallel[100]$, the field
evolution of the Raman active
crystal field modes is quantitatively described by conventional Zeeman splitting of the Pr$^{3+}$ ground state doublet, including the thermally populated upper Zeeman branch at elevated temperature. For $\mathrm{}{B}\parallel[111]$, the spectra separate into responses from the triangular and kagome sublattices, and the CEF excitations of Pr$^{3+}$ on the triangular
lattice exhibit the expected Zeeman shift consistent with full moments polarization. In contrast, the CEF excitations of Pr$^{3+}$ on the kagome
lattice do not split as expected and instead broaden strongly with increasing field. This behavior is inconsistent with a static polarized configuration and is captured phenomenologically by a motional-narrowing description in which the kagome plane moments fluctuate between Zeeman-split levels on a meV timescale. This result offers a natural explanation for the reduced magnetization observed in $\mathrm{}{B}\parallel[111]$ and provides further evidence of the dipole-quadrupole properties of
magnetic moments. It highlights Raman scattering as a sensitive probe of exotic
spin-orbital dynamics in frustrated magnets.
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All authors Yuanyuan Xu, Huiyuan Man, Nan Tang, Li Xiang, Sami Muhammad, Komalavalli Thirunavukkuarasu, Dmitry Smirnov, Satoru Nakatsuji, Natalia Drichko
Strongly Correlated Electrons · Cross-listed from cond-mat.stat-mech
Random-matrix and transport frequencies in eigenstate spectral functions
Kadir Çeven, Rohit Patil, Marcos Rigol et al. (+1 more)
The fact that generic isolated many-body
quantum systems thermalize is understood using the eigenstate thermalization hypothesis (ETH). In recent years, there has been much interest in the behavior of the ETH spectral functions, which characterize the smooth dependence of the variance of the off-diagonal
matrix elements of observables on the associated energy and frequency, and whose low-frequency part contains information about the long-time dynamics. In finite systems described by the ETH, the spectral functions are expected to exhibit plateaus below a characteristic frequency $\omega^{}_{\mathrm{ETH}}$. In this regime, the statistics of the
matrix elements of observables are expected to be described by random
matrix theory. Related frequencies that have been studied in the literature are $\omega^{}_{\mathrm{SFF}}$, which controls the onset of random-
matrix behavior in the spectral form factor, and the transport frequencies $\omega^{}_{\mathrm{tr}}$, which are derived from transport coefficients. However, a direct quantitative comparison of these frequencies is lacking. Using exact diagonalization, we conduct such a comparison for the spectral functions of current operators in clean and disordered
quantum spin ladders with diffusive energy and
spin transport. We find clear evidence for the expected low-frequency plateaus in the ETH spectral functions. For the accessible system sizes, $\omega^{}_{\mathrm{SFF}}$ is consistent with the extent of the plateaus, while the transport frequencies are systematically larger and lie in the nonuniversal regime of the spectral functions. Our findings highlight the need to better understand the origin of these quantitative differences.
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All authors Kadir Çeven, Rohit Patil, Marcos Rigol, Fabian Heidrich-Meisner
Strongly Correlated Electrons
Carrier-mediated spin helices in low-dimensional systems: Josephson-interference features and correlation renormalization
Yung-Yeh Chang and Chen-Hsuan Hsu
Carrier-induced helical magnetism can arise in interacting one-dimensional systems coupled to localized moments. Here, we investigate the coupled-wire sliding-Luttinger-
liquid counterparts with and without valley degrees of freedom, using isolated Tomonaga-Luttinger
liquids as reference limits. The carrier
spin susceptibility mediates a Ruderman-Kittel-Kasuya-Yosida interaction that selects the helical ordering wave vector, while interchannel correlations lock the relative helix phases and stabilize a collective quasi-two-dimensional texture. Using a variational treatment, we estimate the helix-induced partial gap and analyze the reconstruction of the remaining gapless carrier modes. To probe the spatial texture through transport, we incorporate the helix into an anisotropic
superconductor-normal-metal-
superconductor Josephson junction motivated by the coupled-channel structure of twisted bilayer WTe$_2$. We exploit flux focusing near the junction interfaces to make an applied in-plane field a controlled probe of the
spin helix. Relative to junctions without the helix, the helical exchange field modifies the central-lobe width and relative lobe weights. In the transverse-channel geometry, it also produces field-dependent side-lobe asymmetry and central-peak displacement, which remain negligible in the matched references for the parameters considered. The reconstructed carrier sector also exhibits modified local-density-of-states exponents,
spin-relaxation behavior, and competing correlations, with distinct signatures in isolated and coupled-wire systems. Our results connect collective helical order in coupled-wire systems to carrier-sector reconstruction and identify field-tunable Josephson interferometry as a complementary transport probe of the spatial
spin texture.
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Strongly Correlated Electrons
Direct Charge-4e Superconductivity by Mobilizing Bound Quartets
Jin-Tao Jin, Pengfei Li and Yi Zhou
A direct charge-\(4e\)
superconductor exhibits coherent four-electron order without condensation in any charge-\(2e\) pairing channel. We establish three complementary results. First, a particle-number-conserving
Hamiltonian with electron hopping and two-body interactions moves bound quartets efficiently: for electron- and pair-hopping amplitudes \(t\) and \(K\) and local gap \(U_0\), virtual pair transfer produces quartet hopping at order \(K^2/U_0\), whereas electron hopping alone contributes only at order \(t^4/U_0^3\). Second, the microscopic theory identifies an exactly solvable parent
Hamiltonian at the phase-separation boundary. Its ground state combines quartet off-diagonal long-range order and finite phase stiffness without pair condensation, while rigorous bounds establish quartet order beyond the parent in a family with explicit quartet transfer. Third, a single convergent strong-coupling expansion simultaneously controls quartet kinetics and thermodynamic stability and rules out condensation in every pair channel of the microscopic model. On bipartite hypercubic
lattices at half quartet filling, it yields a parametrically controlled homogeneous phase for \(d\geq2\), with quartet order, a linear collective mode, and gapped charge-\(2e\) excitations. Virtual pair transfer thus enables a direct charge-\(4e\) superconducting ground state without pair condensation.
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Strongly Correlated Electrons
Spin-Orbit Induced Confinement of Correlated Bound States in the Continuum
Kai Chen, Junyan Guan, Zhongming Gu et al. (+1 more)
Repulsively bound doublons are two-particle composites formed by strong interactions and are usually separated from the scattering continuum. Introducing
spin-orbit coupling fundamentally alters the underlying band structure, providing a powerful tuning knob to shift these isolated pairs toward this continuum. However, because entering such a regime typically dictates immediate dissociation, whether this coupling can drive these pairs inside while preserving their bound nature constitutes a fundamental unresolved challenge. Here we show that
spin-orbit coupling in the one-dimensional Fermi-Hubbard model can drive doublons into the two-particle scattering continuum. Most of these states hybridize with extended channels and decay, whereas a subset remains decoupled and spatially bound, forming many-body bound states in the continuum (BICs). We map the interacting two-particle problem onto a two-dimensional
lattice of coupled acoustic cavities, and experimentally observe both the radiating doublon continuum and the confined BIC states. These results demonstrate that
spin-orbit coupling can turn selected doublons into interaction-induced BICs, deepening the understanding of continuum physics for interaction-bound pairs.
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All authors Kai Chen, Junyan Guan, Zhongming Gu, Jie Zhu
Strongly Correlated Electrons · Cross-listed from cond-mat.mtrl-sci
Revealing tilt-driven structural heterogeneity in hybrid improper ferroelectrics by spatially-resolved crystallography
Evie Ladbrook, Jon P. Wright and Mark S. Senn
Domain walls in ferroic oxides can host emergent functionalities that differ fundamentally from those of the surrounding bulk, making their microscopic structure central to understanding and controlling macroscopic behaviour. We use scanning three-dimensional X-ray diffraction to map the spatial
evolution of coupled octahedral distortion modes across ferroelastic domain walls in the hybrid improper ferroelectric Ca$_{2.15}$Sr$_{0.85}$Ti$_{2}$O$_{7}$. By combining tomographic reconstruction with
symmetry-adapted analysis of the octahedral rotation and tilt and associated strain modes, we map their spatial
evolution across individual walls in the bulk
crystal. We find that the walls are intrinsically extended, with widths far exceeding those expected for conventional Ising-like ferroic interfaces. The wall structure is characterised by a continuous rotation of the tilt order parameter through a tetragonal intermediate. These results provide new microscopic insight into the structural mechanisms governing ferroelastic wall formation, ferroelectric switching, and emergent functionality at domain walls.
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Strongly Correlated Electrons
Slave-Rotor and Auxiliary Chain Analysis of the Mott Transition in a Modified Periodic Anderson Model
Ankur Majumder and Sudeshna Sen
The Mott-Hubbard transition is a paradigmatic phenomenon driven by strong electronic correlations. We investigate this transition in a three-orbital modified periodic Anderson model using slave-rotor mean-field theory. A minimal two-site cluster extension is introduced to understand the minimal effects of short-range spatial correlations. In comparison to the single-site solution, short-range spatial correlations reveal a shift of the transition point. Going beyond the slave-rotor analysis, we also evaluate the dynamical self-energy and map it onto the boundary Green's function of a non-interacting semi-infinite auxiliary chain. For the metallic phase, the resulting hopping pattern corresponds to a topologically trivial generalized Su–Schrieffer–Heeger chain. This construction provides a framework for exploring the possible topological character of the Mott transition in this model.
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Strongly Correlated Electrons · Cross-listed from hep-th
Critical Kasner scaling from Cauchy-horizon collapse near holographic phase transitions
Ling-Long Gao, Yan Liu and Hong-Da Lyu
We study continuous scalar-hair bifurcations from stationary black holes with a nonextremal Cauchy horizon. Although the exterior deformation vanishes at criticality, the critical zero mode generically develops a logarithmic branch at the reference Cauchy horizon, producing a nonuniform critical limit. We show that the coefficient of this logarithm in the scalar perturbation, together with local Cauchy-horizon data, determines the exponential collapse rate of the Einstein-Rosen bridge. If the post-collapse geometry evolves into a Kasner regime, the boundary order-parameter scaling $O\propto|\lambda-\lambda_c|^\beta$ further implies $ 1-p_t\propto|\lambda-\lambda_c|^{2\beta}. $ Crucially, zero-mode matching fixes both the critical exponents and the associated amplitudes, without any fit to the nonlinear interior. We illustrate this mechanism in the transition from rotating BTZ to hairy rotating black holes. For scalarized RN-AdS$_4$ black branes, we quantitatively verify the predicted Kasner scaling using fully nonlinear numerical solutions. At low temperature, two charged models with identical linear critical data instead approach different infrared endpoints, yielding respectively power-law and inverse-logarithmic Kasner scaling. Thus interiors near a finite-temperature bifurcation are controlled by zero-mode transmission, whereas low temperature scaling is governed by the nonlinear infrared completion.
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Strongly Correlated Electrons
Carrier duality from the convergence of Dirac fermions and high-order van Hove singularities
Meng Lyu, Kaiyi Zhai, Nikolai Peshcherenko et al. (+15 more)
The convergence of highly mobile Dirac
fermions and flat-band heavy electrons offers a paradigm for emergent
quantum phenomena. However, experimental realization of such intriguing state remains elusive. In this study, we report a dual carrier regime in the kagome metal Co3In2S2, wherein the charge transport is governed by high-mobility electrons while the thermodynamic responses exhibit heavy-electron behavior. This exotic duality arises from the coexistence of topological Dirac
fermions and flat-band high-order (4th-order) Van Hove singularities (HOVHSs) at the Fermi surface, as revealed by
magnetic-torque
quantum oscillation and angle-resolved photoemission spectroscopy. The interaction between Dirac and HOVHS-derived carriers can be captured by a minimal two-pocket model, manifesting as sublinear resistivity above ~100 K and field-induced non-Fermi-
liquid behavior at low temperatures. Our study establishes Co3In2S2 as a model platform for exploring many-body physics at the intersection of
topology and correlation effects, and provides a foundational framework for designing
quantum materials hosting diverse emergent states.
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All authors Meng Lyu, Kaiyi Zhai, Nikolai Peshcherenko, Junyan Liu, Jinying Yang, Subir Sen, Binbin Wang, Langsheng Ling, Zhaosheng Wang, Gang Li, Jieyi Liu, Yang Xu, Xiyang Li, Claudia Felser, Yang Zhang, Wujun Shi, Lexian Yang, Enke Liu
Strongly Correlated Electrons
A Majorana Formulation of Time-Dependent Two-Particle Reduced-Density-Matrix Dynamics
Haoran Wang and Alessandro Principi
We introduce a time-dependent two-particle (TP) reduced-density-
matrix algorithm for systems of interacting Majorana
fermions. We close the BBGKY hierarchy at the two-particle level by reconstructing the three-particle reduced density
matrix from lower-order correlations. To stabilize the
evolution, we impose a positivity projection on the two-particle density
matrix while preserving chosen conserved quantities such as the energy. We
benchmark the approach on quenches in the one-dimensional Hubbard model and on flux dynamics in the Kitaev honeycomb model. For the Hubbard quench, TP captures strong-coupling dynamics missed by Hartree–Fock (HF). For the Kitaev quenches, TP accurately reproduces the early-time flux dynamics in several regimes and provides a substantial improvement over HF when two-particle correlations are important. We further show that gauge coherence is essential for flux dynamics. The projection procedure however introduces an effective irreversibility, which affects the long-time dynamics.
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Strongly Correlated Electrons
Decoupling the Magnetic Field Operator as an Independent Operator Class in Stochastic Series Expansion Quantum Monte Carlo
Shijie Jin and Lu Liu
The
Stochastic Series Expansion (SSE)
quantum Monte Carlo method with loop updates is among the most powerful approaches for
quantum spin and
boson systems. In the standard formulation, the
magnetic field term is routinely absorbed into the Heisenberg interactions—a strategy that has proven highly efficient across a wide range of field strengths. In this work, we propose a more general SSE framework in which the
magnetic field operator is treated as an independent operator class, enabling it to participate in Monte Carlo updates on an equal footing with all other operators. Importantly, the field operator and other interaction operators can transform into one another during the update process. We demonstrate this
algorithm using the two-dimensional antiferromagnetic Heisenberg model in a
magnetic field as a concrete example. The simulation results agree with those of the conventional
algorithm, confirming the correctness of the new formulation. A comparison of the integrated autocorrelation time shows that the new
algorithm is competitive. This flexibility not only facilitates measurements of observables associated with operators but also offers potential computational advantages for a broader class of problems.
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