Strongly Correlated Electrons
Anyon Proliferation and Anyon Superconductivity in Higgsing Transitions via Conformal Embeddings
Diego García-Sepúlveda and Da-Chuan Lu
We discuss (2+1)d Chern-Simons Higgsing transitions based on conformal
embeddings and their relation to the proliferation of anyons. These transitions preserve or enlarge the intrinsic topological order despite reducing the gauge group. When the topological order is enlarged, the two phases differ by anyon condensation, and the transition takes an Abelian topological order to a non-Abelian one. In the $SO(N)_{2} \hookrightarrow SU(N)_{1}$ family with $N \geq 3$, the two semiclassical regimes have equivalent intrinsic topological orders but distinct realizations of a global $U(1)$
symmetry. For odd $N$, these are non-Abelian realizations of transitions from fermionic $1/N$ Laughlin states to charge-$2e$ anyon superconductivity coexisting with the same chiral $\mathbb{Z}_{N}$ topological order. The scalar representations are always non-integrable with respect to the UV Chern-Simons level and therefore do not directly label anyons of the un-Higgsed phase, despite defining Wilson lines in the UV. Using heuristic adjoint screening, we propose candidate anyons in the un-Higgsed phase, while branching under the
Higgs subgroup reveals channels corresponding to condensable anyons of the
Higgs phase. We further construct a $\mathrm{Spin}(16)_{1} \to \mathrm{Spin}(9)_{2}$ transition admitting a condensable
algebra that contains a non-Abelian anyon but not all of the allowed gaugable channels in its self-fusion.
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Strongly Correlated Electrons
Designing Strongly Correlated Quantum Phases of Matter with Foundation Neural-Network Quantum States
Alessandro Sinibaldi, Luciano Loris Viteritti, Riccardo Rende et al. (+2 more)
Designing a material with a desired property amounts to solving an inverse problem: finding the couplings of a microscopic
Hamiltonian whose ground state exhibits that property. For strongly correlated
quantum systems, solving this problem efficiently remains largely out of reach. To address this challenge, we present a general framework for ab initio inverse design based on Foundation Neural-Network
Quantum States, a recent approach in which the ground states of a family of
Hamiltonians are encoded in a single variational wave function. Because the ansatz depends explicitly on the couplings, any target property is a differentiable function of them, and the search for the right
Hamiltonian reduces to gradient-based optimization in coupling space. We apply this approach to search for nonmagnetic phases of frustrated Heisenberg models on the square
lattice with an increasing number of free next-nearest-neighbor couplings, aiming to identify new
quantum spin liquid candidates. With a single coupling, the method recovers the known nonmagnetic window of the square $J_1$-$J_2$ Heisenberg model, whereas letting the two diagonal couplings vary independently reveals an extended nonmagnetic region connecting the square-
lattice and anisotropic-triangular-
lattice regimes. In a search space of eight independent couplings within a $2\times2$ unit
cell, which contains several paradigmatic frustrated
spin models, the optimization spontaneously converges to the $J_1$-$J_2$-$\delta$ Heisenberg model, in which the diagonal couplings alternate between two values on neighboring plaquettes, a model recently proposed in the context of altermagnetism. Finite-size scaling up to $16\times16$ clusters in this optimal model shows that the ground state has no
magnetic, dimer, or plaquette order, establishing it as a new
quantum spin liquid candidate, distinct from those previously proposed on the square
lattice.
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All authors Alessandro Sinibaldi, Luciano Loris Viteritti, Riccardo Rende, Federico Becca, Giuseppe Carleo
Strongly Correlated Electrons
adapol: Adaptive pole-fitting for quantum many-body physics
Zhen Huang, Chia-Nan Yeh, Lin Lin et al. (+3 more)
We describe adapol, a Python package for fitting Matsubara Green's functions, self-energies, and hybridization functions by a compact sum of simple poles with real pole locations and
matrix-valued residues. This pole-fitting step arises in many contexts, including hybridization fitting for
quantum impurity solvers based on exact diagonalization, perturbation theory, and tensor networks, the compression of existing pole expansions such as the discrete Lehmann representation, diagrammatic methods based on discrete pole representations, and the analytic continuation of Matsubara Green's functions. adapol uses a modified version of the AAA rational approximation
algorithm to estimate pole locations, and non-convex optimization to refine them. This procedure yields accurate and compact fits in a black-box and noise-robust manner. adapol provides a simple, self-contained interface with extensive documentation and examples, as well as an interface to the TRIQS package.
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All authors Zhen Huang, Chia-Nan Yeh, Lin Lin, Nils Wentzell, Jason Kaye, Hugo U. R. Strand
Strongly Correlated Electrons
Probing Collective and Individual Kondo Screening: Multi-Stage, Multi-Channel Kondo Effects in a $C_3$-Symmetric Four-Impurity Model
Danqing Hu, Jiangfan Wang, Zixiang Hu et al. (+1 more)
Collective screening has been proposed to underlie the basic physics of multi-impurity and
lattice Kondo systems. But how to establish this picture and distinguish it from individual (local) Kondo screening remains a grand challenge. The recently developed auxiliary-bath numerical renormalization group (AUNRG) method provides a key step towards resolving this issue. Its application to the $C_3$-symmetric three-impurity Kondo (3IK) model with a shared electron bath reveals fully screened Fermi
liquid ground states arising from collective screening of cluster
spin degrees of freedom at small Kondo coupling $J_{\rm K}$ and individual (local) screening of local impurities at large $J_{\rm K}$. Here we design a four-impurity Kondo (4IK) model where the probe impurity couples only to the original three Kondo impurities to detect the nature of the screened states. We show that the collective and individual Kondo screenings give rise to emergent multi-stage, two-channel Kondo effect and unstable three-channel Kondo effect, respectively. This suggests a special helicity structure of the screened states and confirms the idea of collective screening in multi-impurity Kondo systems. Our work also demonstrates that the same auxiliary-bath construction can be readily extended to models with additional impurities to explore novel many-body
quantum states with emergent cluster degrees of freedom.
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All authors Danqing Hu, Jiangfan Wang, Zixiang Hu, Yi-feng Yang
Strongly Correlated Electrons · Cross-listed from cond-mat.mes-hall
Topological Transverse Transport without a Gap in Critical Topological Flat Bands
Chang-geun Oh, Tomoki Ozawa and Jun-Won Rhim
Quantized Hall transport is traditionally anchored to a bulk spectral gap, which isolates the occupied subspace and exponentially suppresses thermal deviations. Recently discovered critical topological flat bands (CTFBs) challenge this paradigm: an exactly flat band touches a dispersive continuum while retaining a well-defined integer Chern number. However, their finite-temperature transverse transport properties remain entirely unexplored. Here, we develop a low-temperature theory of the intrinsic electrical, thermoelectric, and thermal Hall responses in CTFBs. At fixed particle number, the macroscopic flat-band degeneracy forces a singular Lambert-$W$ drift of the chemical potential, generating an algebraic-logarithmic hierarchy of low-temperature corrections: $T\ln(1/T)$ for electrical Hall, $T[\ln(1/T)]^2$ for thermoelectric Hall, and $T[\ln(1/T)]^3$ for thermal Hall conductivity, replacing the activated thermal protection of a gapped Chern
insulator. By contrast, externally pinning the chemical potential to the flat-band energy locks the flat band to half occupation at any nonzero temperature, obstructing the recovery of the fully filled topological ground state as $T\to0^+$. Our results establish that a bulk spectral gap is unnecessary for zero-temperature Hall quantization, but indispensable for its exponential thermal protection.
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Strongly Correlated Electrons
Impurity-induced Friedel oscillations and Wigner crystallization in Luttinger liquids via Unified Field Bosonization Technique
Soundarya P, Venkata Suryanarayana M and Joy Prakash Das
We present an analytical study of impurity-induced density correlations in interacting one-dimensional Luttinger
liquids using the Unified Field Bosonization Technique (UFBT). Unlike conventional approaches that treat impurities perturbatively, UFBT incorporates localized impurities exactly at the free-
fermion level while treating interactions non-perturbatively. Closed analytical expressions for fermionic Green functions and density-density correlation functions are obtained for strongly inhomogeneous systems, enabling a unified description of the impurity-induced $2k_F$ Friedel oscillations and the $4k_F$ Wigner-
crystal like correlations. The corresponding scaling behaviour is derived analytically, revealing a crossover in the dominant long-distance correlations at $g=1/3$: Friedel correlations dominate for $g>1/3$, whereas Wigner-
crystal like correlations become dominant for $g<1/3$, corresponding to the regime of sufficiently strong repulsive interactions. A reflection-coupled harmonic analysis is developed to account for the left-right mixing induced by impurity backscattering and to consistently reproduce the resulting density correlations. The spinless limit is also obtained as a direct reduction of the spinful formulation. These results provide an analytically controlled framework for describing impurity-induced and interaction-driven density correlations in strongly inhomogeneous one-dimensional
quantum systems.
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Strongly Correlated Electrons · Cross-listed from cond-mat.stat-mech
Many-body topology in parity-preserving tensor networks
Maksimilian Usoltcev, Nguyen Hanh Dung, Carolin Wille et al. (+2 more)
Planar parity-preserving tensor networks (ppTNs) admit a fermionic formulation in which the Gaussian, efficiently contractible limit is deformed by local interactions. We investigate how many-body methods can be used to analyze such contractions in a minimal two-parameter ppTN. Its contraction is simultaneously an interacting fermionic partition function, a loop gas, a deformed toric-code norm, and a quartic Ising model, allowing the same phase diagram to be approached with complementary tools. At its center lies a `topological island', characterized beyond the Gaussian limit by a boundary-twist $\mathbb Z_2$ indicator that reduces to Chern-number parity and admits a loop-winding interpretation under duality. Fermionic perturbation theory predicts the interacting phase boundaries, tensor-network numerics establish their critical behavior, and the loop and
spin descriptions reveal a self-dual line with a $c=1$ four-state-Potts multicritical fixed point.
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All authors Maksimilian Usoltcev, Nguyen Hanh Dung, Carolin Wille, Matteo Rizzi, Alexander Altland
Strongly Correlated Electrons
Entropy-Driven Altermagnetism from Thermal Magnons
Tanaya Halder, Ashis K. Nandy and Anamitra Mukherjee
We identify a route to altermagnetism driven by
entropy upon heating and demonstrate it in a minimal square-
lattice antiferromagnet. An exchange modulation is entropically favored because the resulting momentum-dependent
magnon splitting increases the
magnon entropy, thereby lowering the free energy and favoring altermagnetism. We derive an instability criterion for this exchange-modulated state, predict its temperature-driven reentrant behavior, and show that its overlap with Néel order defines a finite-temperature altermagnetic phase. Variational
spin-wave theory,
spin–
lattice Monte Carlo, and cluster diagonalization establish the
entropy-driven instability and its coexistence with
magnetic order. The resulting state supports a transverse
spin conductivity. The mechanism provides a route to thermally induced altermagnetism in compensated magnets coupled to sufficiently soft physical modes.
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Strongly Correlated Electrons · Cross-listed from cond-mat.mes-hall
Atomic-Scale Imaging of Lattice Relaxation and Topological Flat Bands in Helical Trilayer Graphene
Shudan Jiang, Zonglin Li, Yu Gu et al. (+15 more)
Helical trilayer
graphene (HTG) has emerged as a highly tunable moire
quantum material that hosts strong electronic correlations and nontrivial band
topology. However, the atomic-scale
lattice structure and local electronic properties have remained largely unexplored. Here we present a comprehensive real-space study of HTG using a combination of scanning near-field optical microscopy and low-temperature scanning tunneling microscopy. We directly image supermoire
lattice relaxation, revealing large triangular domains separated by sharp domain walls, as well as stripe domains connected by smoothly varying boundaries. Atomic-scale spectroscopy uncovers flat bands with a honeycomb electronic texture and one-dimensional boundary states confined to domain walls. By systematically varying the twist angle, we identify a magic angle of approximately 1.9{\deg}, substantially larger than the 1.6 degree predicted by theory. Our results establish a direct microscopic link between
lattice relaxation and flat bands in HTG.
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All authors Shudan Jiang, Zonglin Li, Yu Gu, Liang Liu, Dandan Guan, Yaoyi Li, Hao Zheng, Canhua Liu, Kenji Watanabe, Takashi Taniguchi, Shengwei Jiang, Xiaoxue Liu, Zhiwen Shi, Guorui Chen, Jinfeng Jia, Tingxin Li, Can Li, Shiyong Wang
Strongly Correlated Electrons
Strong Dimerization and Field-Induced Reconstruction of the Low-Energy Spectrum in $\mathrm{Cu}_3(\mathrm{OH})_4(\mathrm{HCO}_2)_2$
Sk Saniur Rahaman and S. R. Hassan
We investigate the field-dependent low-energy thermodynamics of the distorted triangular
quantum antiferromagnet $\mathrm{Cu}_3(\mathrm{OH})_4(\mathrm{HCO}_2)_2$ using a sector-resolved Superblock Diagonalization Method (SBDM) supplemented by a transfer-
matrix treatment of weakly coupled layers. The strong exchange hierarchy, dominated by the Cu1–Cu1 intradimer coupling $J_2=150\,\mathrm{K}$, separates a high-energy dimer sector from a much softer
magnetic manifold formed predominantly by the Cu2 moments. In the 24-site cluster, sixteen Cu1
spins form the strongly bound sector while eight Cu2
spins remain magnetically active; polarization of these eight
spins gives $S^z=4$ compared with $S^z_{\rm sat}=12$, providing a direct microscopic origin for the one-third magnetization scale. The finite-temperature thermodynamics reveals a non-monotonic field
evolution of the low-energy scale: the dominant $C/T$ feature softens with increasing field, reaches a minimum near the field region around $2\,\mathrm{T}$, and subsequently hardens as the low-temperature magnetization approaches $M_{\rm sat}/3$. Temperature and field sweeps thus expose a common field-induced spectral reconstruction, while the strongly reduced
entropy reflects the restricted number of thermally active degrees of freedom below the dimer excitation scale. Our results identify strong-dimer-induced reduction of the active
magnetic Hilbert space, followed by field-driven reorganization of the residual
spin sector, as the common microscopic origin of the one-third
magnetic response and the non-monotonic low-temperature thermodynamics.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Fault Tolerant Quantum Phases of Matter
Colin V. Coane, Shouzhen Gu and Aleksander Kubica
We introduce a classification of
quantum phases of mixed states based on the ability to preserve and fault tolerantly transfer information. We formulate phase equivalence between sets of states that encode logical
quantum information and are connected by shallow local channel
circuits assisted by local measurements and global classical communication of measurement outcomes, where all
quantum operations, including measurements, must be robust to noise. We show that the existence of a recovery threshold for local noise is a property of an entire phase. We prove that any two sets of states with nonzero thresholds that are related by finite-depth local channel
circuits belong to the same fault tolerant phase. Our approach leads to a classification of subsystem codes without favoring any state of the gauge subsystem, and we demonstrate phase equivalence between 2D and 3D color codes using dimensional jumps within the 3D gauge color code. Lastly, we study how syndrome structure affects fault tolerance in
circuits with measurements. We show that qudit stabilizer codes with extended syndromes permit single-shot state preparation, whereas a broad class of shallow
circuits measuring point-like syndromes, including state preparation for 2D topological codes and non-Abelian topological orders with solvable anyon theories, is not fault tolerant.
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Strongly Correlated Electrons
$\mu$SR measurements of 3D Ising ferromagnetism in bulk Fe$_3$GeTe$_2$ crystals
M. N. Wilson, J. Huang, T. J. Hicken et al. (+4 more)
Fe$_3$GeTe$_2$ is a quasi-two-dimensional itinerant ferromagnet with a van-der-Waals layered structure that exhibits substantial
magnetic anisotropy. In bulk samples, this material becomes magnetically ordered below 220~K, while in thin samples, the gate-tunability of the ferromagnetic moment has attracted significant interest. Alongside high-temperature ferromagnetism, a low-temperature
magnetic state occurs whose nature has not been conclusively identified, with some studies suggesting a transition between ferromagnetism and antiferromagnetism with temperature. Here we present magnetometry and $\mu$SR data that demonstrate that Fe$_3$GeTe$_2$ exhibits three-dimenional Ising-like ferromagnetism over the entire temperature range between $T_{C}=220$~K and 2~K. The feature at 170~K that has previously been proposed to be a transition to antiferromagnetism is instead likely to represent a domain-freezing transition.
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All authors M. N. Wilson, J. Huang, T. J. Hicken, D. A. Mayoh, B. M. Huddart, G. Balakrishnan, T. Lancaster
Strongly Correlated Electrons · Cross-listed from quant-ph
Optimal local recovery cannot alter critical orthogonality exponents in quantum spin environments
Zhixuan Zhao and Jun Li
We prove a local amplitude-ratio bound for positive ground states and an explicit reverse comparison for fidelity under finite-region erasure. An exact
lattice calculation for a connected critical Ising chain gives amplitude exponent $1/8$, preserved by arbitrary optimal control on any fixed
spin set and, at the level of logarithmic exponents, on $o(\log N)$
spins. We derive the finite Cauchy product and its uniform strip asymptotics, and document exact two-
spin optimization and an interferometric protocol for measuring the recovery. A separate finite-mediator
theorem quantifies local compression and a decoder while retaining the rest of the environment exactly. We also give a ground-preparation Ramsey bound, counterexamples to stronger projected-state inferences, and independent full-
Hamiltonian calculations.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Excitation gap of a blockade structure with $\mathbb{Z}_2$ topological order
Simon Fell, Tobias F. Maier, Hans Peter Büchler et al. (+1 more)
Mathematically rigorous statements on the spectral gap of
quantum many-body systems in the thermodynamic limit are notoriously difficult to prove – yet they are of fundamental importance for classifying
quantum phases of matter. Here we prove the existence of a finite excitation gap for a particular
Hamiltonian which was proposed in [T. F. Maier et al., PRX
Quantum 6, 030340 (2025)] and is motivated by the Rydberg platform. The
Hamiltonian exhibits only two-body blockade interactions between two-level systems and has a topologically ordered ground state in the toric code phase. We show that our result also applies to a broader class of blockade
Hamiltonians which realize non-Abelian
quantum double phases and were proposed in [H. P. Büchler et al., Phys. Rev. B 114, 065113 (2026)]. The proof builds on known gap stability results and exploits the local
symmetry of the studied models.
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All authors Simon Fell, Tobias F. Maier, Hans Peter Büchler, Nicolai Lang
Strongly Correlated Electrons
Weyl superconductivity from Feshbach resonance in the three-dimensional repulsive Hubbard model
Taekyoung Kim, Pit Bermes, Giorgia A. Busin et al. (+1 more)
Motivated by the first experimental realization of the antiferromagnetic phase transition in the three-dimensional Fermi-Hubbard model, we present a theoretical study of the model's 3D superconducting phase. By formulating a 3D extension of the Feshbach mechanism, we provide a unified microscopic picture at strong coupling in which pairing is driven by near-resonant bound states of dopants. These long-lived bound states acquire a qualitatively different internal structure in three dimensions compared to their two-dimensional counterparts, giving rise to a distinct superconducting state, namely a time-reversal
symmetry breaking $d_{x^2-y^2}+id_{z^2}$ pairing state. We also provide an estimate of the corresponding critical temperature, and provide evidence that the resulting superconducting phase hosts gapless Weyl points. Our results represent a new milestone for the field of
quantum simulation, challenging experiments and large-scale numerics alike to test our predictions.
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All authors Taekyoung Kim, Pit Bermes, Giorgia A. Busin, Fabian Grusdt
Strongly Correlated Electrons
Quantum Well Resonant Tunneling Diode Probe of Correlated States in Twisted Bilayer MoS$_2$
Chengjie Zhou, Jin-Xin Hu, Sihong Xu et al. (+4 more)
Moiré superlattices formed in transition metal dichalcogenides (TMDs) offer a versatile platform for exploring emergent
quantum phases arising from strong electronic correlations. In this work, we develop a new experimental platform, the
quantum well resonant tunneling diode (QWRTD), to probe the electronic landscape of $\approx 57^\circ$ twisted bilayer MoS$_2$ (tMoS$_2$). By measuring the differential conductance ($dI/dV_{\text{Probe}}$) as a function of filling factor $\nu$ and displacement field $D$, we observe a robust integer correlated insulating state at $\nu = 1$ that persists across the measured displacement field range. Furthermore, we identify a displacement-field-induced fractional insulating state at $\nu = 3/4$ for $D < -75$~mV/nm. Temperature- and
magnetic-field-dependent measurements characterize this $\nu = 3/4$ state as a potential generalized Wigner
crystal. These correlated states are also observed in another device with a similar twist angle ($\approx 56.5^\circ$). Our results provide direct evidence of correlated states in near-AB-stacked tMoS$_2$ and establish QWRTD as a powerful experimental tool for investigating strong correlations and
topology in van der Waals
heterostructures.
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All authors Chengjie Zhou, Jin-Xin Hu, Sihong Xu, Zijing Jin, Hui Li, Kam Tuen Law, Jiannong Wang
Strongly Correlated Electrons
Chiral quantum chaos around exponentially many zero modes in the quantum breakdown model
Kohei Kawabata, Kinya Guan and Hosho Katsura
The
quantum breakdown model is a model of randomly interacting
fermions, motivated by the physics of dielectric breakdown. Here, we establish classification of
symmetry and
quantum chaos in a zero-dimensional, all-to-all-interacting version of the
quantum breakdown model. It exhibits the $\mathbb{Z}_4$ periodicity with respect to the number of fermionic modes, reminiscent of the
symmetry classification of the Sachdev-Ye-Kitaev model. A unique feature of the
quantum breakdown model is that it realizes all the five classes with chiral
symmetry and hosts an exponentially large number of many-body zero modes protected by the chiral index. We elucidate the separation and scaling of the spectral gap and demonstrate the
symmetry-enriched hard-edge spectral statistics as signatures of
quantum chaos in the chiral
symmetry classes.
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Strongly Correlated Electrons
Varying A-site radius and size disorder to tune magnetic ordering in compositionally complex perovskite oxides
Madeleine Geers, Ravi Kiran Dokala, Roland Mathieu et al. (+1 more)
A long standing goal of magnetochemists is to be able to control ordering temperatures through compositional engineering. Here we report the synthesis of a perovskite oxide with twelve cations accommodated within a single phase solid solution, AM7O$_3$, A = La$_{\frac{1}{5}}$Sm$_{\frac{1}{5}}$Gd$_{\frac{1}{5}}$Nd$_{\frac{1}{5}}$Dy$_{\frac{1}{5}}$ (A5), and M7 = Ti$_{\frac{1}{7}}$Cr$_{\frac{1}{7}}$Mn$_{\frac{1}{7}}$Fe$_{\frac{1}{7}}$Co$_{\frac{1}{7}}$Ni$_{\frac{1}{7}}$Cu$_{\frac{1}{7}}$. Bulk magnetometry measurements for A5M7O$_3$, as well as for A = La, Gd and La$_{\frac{1}{2}}$Gd$_{\frac{1}{2}}$, show that all these compounds magnetically order as ferrimagnets between 89 and 115 K. We find that the
magnetic properties are influenced by considering a combination of the size disorder parameter alongside the A-site cationic radii and valence electrons.
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All authors Madeleine Geers, Ravi Kiran Dokala, Roland Mathieu, Rebecca Clulow
Strongly Correlated Electrons
Multipartite entanglement hidden in vector-chiral correlations of spin-1/2 chains
Tokuro Shimokawa
Characterizing
entanglement in
quantum materials through experimentally accessible observables remains a central challenge.
Quantum Fisher information associated with sums of one-site
spin operators provides one route by linking
entanglement to measurable
magnetic response functions. Extending this approach to local composite observables requires new
entanglement bounds. Here we establish a rigorous bound for the total nearest-neighbour vector chirality of periodic
spin-$1/2$ chains with an even number of sites. The
quantum Fisher information per
spin cannot exceed $k+1$ for any $k$-producible state, so exceeding this bound certifies
entanglement depth of at least $k+1$. Combining infinite density-
matrix renormalization group and thermal pure
quantum-state calculations, we demonstrate multipartite
entanglement encoded in vector-chiral correlations at zero and finite temperatures in an extended $J_1$-$J_2$ XXZ chain. The
spin-current coupling between vector chirality and electric polarization offers, in principle, access to this witness through dielectric loss spectroscopy in multiferroic magnets, extending
entanglement diagnostics beyond dipolar
spin correlations.
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Strongly Correlated Electrons
Tunability of the structural and magnetic transition in kagome material: PrIr$_3$B$_2$
Gayathri V, Irshad K A, Sathishkumar M et al. (+2 more)
We report the temperature and pressure tunability of an unusual structural transformation associated with a two-step metal-
insulator-metal (MIM) transition in the kagome
lattice compound PrIr$_3$B$_2$ using synchrotron X-ray powder diffraction. At ambient conditions of temperature and pressure, the monoclinic ($C2/m$) and the hexagonal ($P6/mmm$) phases coexist as twinned structure in the
crystal. As the temperature (pressure) is decreased (increased), PrIr$_3$B$_2$ converts fully to monoclinic structure at $T =$ 280 K (at ambient pressure) and $P =$ 1.2 GPa (at room temperature). Temperature dependence of the monoclinic structure at ambient pressure presents complex
evolution of
lattice parameters with weak but clearly discernable anomalies at \SI{\sim 250} {\K} and \SI{\sim 110} {\K}, which are correlated with the second MIM transition and the linear to nonlinear temperature-dependent resistivity crossover, respectively. These anomalies are likely due to some charge order state causing a partially gapped Fermi surface. The
magnetic phase diagram of PrIr$_3$B$_2$ is also investigated from anisotropic measurements. At 10 K, a superzone gap opens near the antiferromagnetic transition, which does not close even in the polarized state. From the tunability of the
crystal structure and
magnetic and electronic ground state, promising electronic orders are indicated in this kagome metallic magnet.
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All authors Gayathri V, Irshad K A, Sathishkumar M, Boby Joseph, S. Manni
Strongly Correlated Electrons · Cross-listed from cond-mat.stat-mech
Interdependent-Network Criticality without a Second Network: Cascading Collapse of the Joule-Coupled Insulator-Metal Transition in $VO_2$
Ouriel Gotesdyner, Michal Wasserman, Hodaya Kaster et al. (+5 more)
When driven by a large enough electric field or current, the insulating state of vanadium dioxide ($VO_2$) typically collapses abruptly into the metallic state (the
insulator-metal transition, IMT) following a brief incubation delay. These incubation delays, typically lasting microseconds or less, have been analyzed predominantly through macroscopic electro-thermal modeling, providing little statistical insight into the transition dynamics. Here, we investigate the electrically driven IMT in a two-dimensional $VO_2$
lattice and demonstrate that the material behaves as a complex, interdependent network despite being a single structural entity. Because metallic domains dissipate significantly more Joule heat than insulating regions, each switching event raises the Joule heating of the network, resulting in network dependency and triggering a cascading chain reaction. Combining time-resolved resistance measurements with a Joule-coupled resistor-network model and interdependent-network theory, we observe an abrupt (first-order) transition preceded by an anomalously long incubation plateau lasting thousands of seconds. During this metastable plateau, an effective branching factor of the switching activity approaches unity at criticality, and the plateau lifetime diverges with exponent $\zeta=1/2$; the order parameter scales with exponent $\beta=1/2$. These signatures coincide with those predicted for interdependent networks, indicating that dissipative Joule coupling alone can drive mixed-order catastrophic cascades in a single-network correlated-oxide system.
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All authors Ouriel Gotesdyner, Michal Wasserman, Hodaya Kaster, Yosi Abulafia, Avital Fried, Bnaya Gross, Shlomo Havlin, Amos Sharoni
Strongly Correlated Electrons
Eigenstate thermalization at the edge of the many-body spectrum
Arnav Pushkar, Pranay Patil, Soumya Bera et al. (+2 more)
It is well-known that thermalization breaks down in presence of an extensive number of
symmetries or conservation laws that are mutually compatible or commuting with each other. We ask here how an extensive number of mutually incompatible local
symmetries govern eigenstate thermalization (ETH). We will investigate this through models within the class of bond-dependent $\mathbb{Z}_2$-symmetric
quantum spin-$\frac{1}{2}$
Hamiltonians that naturally admit this structure. This leads to exponentially large degeneracies in the spectrum governed by the incompatible
symmetry structure. Here, using spectral diagnostics, we show that non-integrability can survive despite extensively many conserved quantities when they are incompatible. Furthermore, we show that ETH behavior persists deep into the many-body spectral edge due to this structure. In other words, incompatible local
symmetries enable a mechanism to obtain enough thermodynamic
entropy at low excitation energy densities to make ETH operational or predictive near the ground state.
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All authors Arnav Pushkar, Pranay Patil, Soumya Bera, Masaki Tezuka, Sumiran Pujari
Strongly Correlated Electrons · Cross-listed from quant-ph
Optical studies of negative g-factor dopants in an antiferromagnet: Nd:GdVO$_4$
Lachlan W. Cronin, Masaya Hiraishi, Luke S. Trainor et al. (+1 more)
Neodymium-doped gadolinium vanadate (Nd:GdVO$_4$) is a popular
laser material at room temperature. It has received limited
attention for
quantum technologies because of the linebroadening effects of disordered gadolinium
spins in the host. Here we investigate the optical properties at temperatures below the 2.5 K Néel temperature, revealing narrow optical transitions. We demonstrate that rare earth ions in
magnetic hosts give us a new way of observing the signs of
magnetic g-factors. The interplay between the exchange and Zeeman interactions means that we see clear evidence of negative g-factors. These results provide a detailed spectroscopic foundation for Nd:GdVO$_4$ and expand the understanding of its candidacy as a material for hybrid
quantum systems.
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All authors Lachlan W. Cronin, Masaya Hiraishi, Luke S. Trainor, Jevon J. Longdell
Strongly Correlated Electrons
Quantum quenches of scar states in the Affleck-Kennedy-Lieb-Tasaki model via Clifford augmented tensor network simulation
Azar C. Nakhl, Ben Harper, Muhammad Usman et al. (+1 more)
Clifford augmented methods have emerged as a powerful technique to simulate
quantum circuits and many-body systems by exploiting the stabiliser structure found in said systems, whilst additionally enabling one to readily quantify the non-stabilizerness (i.e.\ magic) present. In this work, we utilise a qudit Clifford augmented simulation method to probe the presence of magic in the Affleck-Kennedy-Lieb-Tasaki (AKLT) model, finding that its ground state and scar states are highly magical as quantified by their Stabiliser Rényi
Entropy (SRE). Nevertheless, owing to its low
entanglement structure, these states are still readily expressible as a Clifford augmented
Matrix Product State with low bond-dimension and moreover may be time-evolved using the Clifford augmented time-dependent variational principle (TDVP)
algorithm. We utilise Clifford augmented TDVP to study the string order dynamics in the scar states of the AKLT model after a quench within the Haldane phase to the anti-ferromagnetic Heisenberg
Hamiltonian. We observe that there is a decay of string order following the quench, which is more pronounced with increasing bimagnon number. This finding highlights the sensitivity of string order in the AKLT scar states to
symmetry-preserving quenches, even when the initial and final
Hamiltonians belong to the same topological phase.
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All authors Azar C. Nakhl, Ben Harper, Muhammad Usman, Thomas Quella
Strongly Correlated Electrons · Cross-listed from cond-mat.mes-hall
Optical observation of interlayer spin correlation
Akiyoshi Park, Pranshoo Upadhyay, Andrey Grankin et al. (+16 more)
Spin correlations govern numerous collective behaviors of
quantum materials, underpinning exotic phenomena such as unconventional superconductivity and topological magnetism. In layered materials, the interlayer
spin correlation is important because it characterizes the
magnetic ground state and determines
spin transport across the interface. Yet interlayer
spin correlations have remained hard to measure directly, leaving one of the most basic quantities of two-dimensional magnetism out of experimental reach. Here we provide the first direct optical probe of interlayer
spin correlations, using two-
magnon Raman scattering in the van der Waals antiferromagnet (AFM) CrSBr, in remarkable agreement with a microscopic
spin-wave model without any fitting parameter. Moreover, the two-
magnon channel switches on only in the AFM state and vanishes when a
magnetic field takes the
crystal to a ferromagnetic state. We furthermore establish an
exciton-mediated variant of the technique, where tuning the
laser near the
exciton resonance enhances the signal roughly tenfold due to the
exciton's large oscillator strength.
Magnon-pair Raman spectroscopy thus opens a direct optical window into interlayer
spin correlations in van der Waals magnets, extendable to twisted bilayers and proximity-coupled
heterostructures.
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All authors Akiyoshi Park, Pranshoo Upadhyay, Andrey Grankin, Emil Viñas Boström, Mahdi Ghafariasl, Hassan Alnatah, Masoud Mohammadi-Arzanagh, Gautam Nambiar, Beini Gao, Alireza Alvandi, Sakthi Rajmano Madhan Kumar, Ghadah Alshalan, Isaac Sherwood, Mahmoud Jalali Mehrabad, You Zhou, Arun Ramanathan, Xavier Roy, Angel Rubio, Mohammad Hafezi
Strongly Correlated Electrons
Sign problem and criticality in world-line quantum Monte Carlo methods
Rubem Mondaini and Richard T. Scalettar
Discussions of the sign problem usually focus on its role as the primary limitation of the applicability of
quantum Monte Carlo methods for reliably solving
quantum many-body models. Its behavior as a function of spatial
lattice size, doping, temperature, and interaction strengths has been carefully characterized within the determinant
quantum Monte Carlo
algorithm. Here, we consider the much less well-explored question of the temperature- and size-dependence of the sign problem in the world-line
quantum Monte Carlo method. We review how, in this
algorithm, even sampling the partition function of free
fermions yields a sign problem, which we connect to non-analytic behavior in the corresponding reference model, hard-core
bosons on a
lattice. The latter exhibits a finite-temperature Kosterlitz-Thouless phase transition in 2D, and we show how this non-analytic behavior is imprinted on the average sign of the weights for the corresponding free
fermion 2D tight-binding model. Our results thus show how phase-transition information can remain encoded in the sign problem even after direct sign sampling becomes impractical.
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