Bulletin of the American Physical Society
2023 APS March Meeting
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session S30: Strongly Correlated Systems, Including Quantum Fluids and Solids XVI |
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Sponsoring Units: DCMP Chair: Rodrigo Alves Pimenta, University of Manitoba Room: Room 222/223 |
Thursday, March 9, 2023 8:00AM - 8:12AM |
S30.00001: Free-fermionic quantum chains with inhomogeneous couplings Rodrigo Alves Pimenta, Francisco C Alcaraz, Jesko Sirker, Rodrigo Alves Pimenta A new family of free-fermionic quantum spin chains with multispin interactions was recently introduced. In this work, we argue that it is possible to build quantum Ising chains with inhomogeneous couplings with the same spectrum of the multispin chains. This is done by associating an antisymmetric tridiagonal matrix to the polynomials that characterize the quasi-energies of the system via a modified Euclidean algorithm. The phase diagram of the inhomogeneous models is investigated numerically and a formula for the order parameter is conjectured. The phase diagram is characterized by gapped phases separated by critical hyperplanes with order-disorder transitions depending on the parity of the number of generators of the Hamiltonian, pointing out an underlying topological phenomena. |
Thursday, March 9, 2023 8:12AM - 8:24AM |
S30.00002: Non-Invertible Symmetries and Phase Transitions in Three Dimensions Anuj Apte, Clay Cordova, Ho-Tat Lam Quantum systems in 3+1-dimension that are invariant under gauging a $G^{(1)}$ one-form symmetry contain non-invertible topological defects which can be obtained by gauging in half of spacetime. We show that a symmetry preserving gapped phase is incongruous with the existence of certain duality defects. These duality defects are realized in Abelian lattice gauge theories and hence elucidate the nature of phase transitions in these systems. |
Thursday, March 9, 2023 8:24AM - 8:36AM |
S30.00003: Scanning SQUID microscopy (SSM) on van der Waals heterostructure with in situ uniaxial strain Ruiheng Bai, Brian T Schaefer, Alexander Jarjour, Katja Nowack Van der Waals (vdW) materials, such as graphene and transition metal dichalcogenides, are atomically-thin, crystalline materials that exhibit a rich variety of electronic phenomena. Application of uniaxial strain can be a powerful tool to alter the properties of materials by breaking symmetry and modulating electronic structure. SSM probes local magnetization, electronic transport and magnetic response, which can give insights into the electronic phenomena observed in vdW materials. Our goal is to implement local magnetic measurements using an SSM on uniaxially strained vdW materials. Our setup is based on a commercial piezoelectric strain cell and devices fabricated on a polyimide substrate. In this talk, we report our progress towards using this approach to apply strain to vdW materials and integration with SSM. |
Thursday, March 9, 2023 8:36AM - 8:48AM |
S30.00004: Quantum Critical Scaling and Magnetic Order of the Quasi-One-Dimensional Heavy Fermion System Yb(Fe_{1-x}Co_{x})_{5}P_{3} Eric D Bauer, Keenan Avers, Mitchell Bordelon, Ashley Weiland, Yu Liu, Clarina dela Cruz, Sean Thomas, Priscila Rosa, Joe D Thompson, Jon Lawrence, Mucio A Contintentino, W. P Halperin, Filip Ronning Quantum criticality has been an organizing principle to explain the behavior of many families of quantum materials including the high-temperature cuprate and iron-based superconductors and f-electron heavy fermion compounds. Most work to date has focused on quantum criticality with two-dimensional (2-D) and 3-D fluctuations. Strong quantum fluctuations are expected in quasi-1-D materials and have recently been explored in 1-D f-electron materials such as CeRh_{6}Ge_{4} [1], Yb_{2}Pt_{2}Pb [2], and YbAlO_{3} [3]. |
Thursday, March 9, 2023 8:48AM - 9:00AM |
S30.00005: First-order quantum phase tranistion in a hybrid transition metal dichalcogenide compound Haim Beidenkopf, Abhay K Nayak, Nurit Avraham, Binghai Yan, Achim Rosch, Yotam Roet, aviram steinbock, Jahyun Koo, Amit Kanigel, Avior Almoalem, Irena Feldman A small change in the crystal structure of a material can completely modify its electronic properties. This is the case in the transition metal dichalcogenide TaS_{2} where a slight rotation of the sulphur atoms from the trigonal prismatic 1H structure to the octahedral 1T varies it from a superconductor to a Mott insulator possibly hosting a spin liquid state. We have studied 4Hb-TaS_{2} that interleaves the 1T and 1H polytypes. This has allowed us to investigate using scanning tunneling spectroscopy the fate of a Mott insulator when coupled to a metal. We find a sharp first order quantum phase transition between a flat band and a Kondo cluster states. It is induced by the combination of electric field and temperature as well as by tuning the inter-layer coupling with the scanning tunneling microscope's tip. The transition line suggests it is governed by the difference in compressibility of the two states involved. The 4Hb-TaS_{2 }system thus offers a platform to investigate the evolution of Kondo lattices from isolated Kondo impurities via an intermediate correlated Kondo cluster state. |
Thursday, March 9, 2023 9:00AM - 9:12AM |
S30.00006: Temperature Dependence of the Charge-Density-Wave Depinning in Quasi-2D 1T-TaS_{2}/h-BN Heterostructures JONAS O BROWN, Alexander A Balandin, Tina T Salguero, Fariborz Kargar, Sergey Rumyantsev, Nicholas Sesing, Adil Rehhman, Maedeh Taheri The 1T polymorph of TaS_{2} is one of the 2D materials that reveal several charge-density-wave (CDW) phase transitions in the form of resistivity changes and hysteresis. The CDW phase is a periodic modulation of the electronic charge density, accompanied by distortions in the underlying crystal lattice, and it may be commensurate, nearly commensurate, or incommensurate with the underlying crystal lattice [1]. Since the commensurate and nearly-commensurate CDWs are locked to the lattice, there is a large energy barrier to translating the CDW across the lattice. Therefore, it was generally believed that the depinning and sliding of CDW could only occur in the incommensurate phase. However, in some materials, I-V measurements have shown depinning and sliding below the C-CDW transition temperature. We demonstrated that the CDW depinning in 2D CDW materials is substantially different from that in “conventional” CDW materials with quasi-1D crystal structures [2]. We discuss the temperature dependence of the depinning threshold in quasi-2D 1T-TaS_{2}/h-BN heterostructures. The depinning point was determined as the onset of current instabilities revealed from the differential I-V characteristics. The obtained results are expected to increase the functionality of 2D CDW devices. |
Thursday, March 9, 2023 9:12AM - 9:24AM |
S30.00007: Holographic theory of symmetry protection of gaplessness and continuous phase transitions in 1+1D Arkya Chatterjee, Xiao-Gang Wen It has been recently understood that phases of a bosonic lattice model with a finite symmetry are characterized by a topological order (TO) in one higher dimension. Lagrangian condensable algebras (LCAs) of a 2+1D TO correspond to its gapped boundaries, while non-Lagrangian ones (NLCAs) describe gapless ones. The above holographic point-of-view suggests that gapped and gapless states in 1+1D correspond to LCAs and NLCAs respectively. Specifically, a continuous phase transition between two gapped phases corresponds to an NLCA. This NLCA then constrains the possible CFTs that may describe the transition, if continuous. Moreover, automorphism symmetries of the 2+1D TO lead to dualities between different parts of the global phase diagram of the boundary theory. For the simplest non-Abelian symmetry group S_{3}, we find a duality that identifies the transition between the S_{3} symmetric phase and the trivial phase with that between the Z_{3} and Z_{2} symmetric phases. So if one of them is continuous, the other must be too. We identify potential gapless CFTs that may describe this transition. Complementary to this, we numerically study the phase diagram of an S_{3} symmetric tensor network model in 1+1D, realizing all the phases mentioned above. To investigate the implications of our holographic approach to a theory with a fusion category symmetry, we study the so-called “golden chain” using tools developed above. |
Thursday, March 9, 2023 9:24AM - 9:36AM |
S30.00008: Topological Entanglement Negativity of Conformal Field Theory Wonjune Choi, Michael Knap, Frank Pollmann In condensed matter physics, conformal field theory (CFT) plays an important role in describing phase transitions and quantum phases of matter. Due to the strong symmetry constraints, a few CFT data are sufficient to determine the correlation functions among local operators. However, it is still an open question what is the complete set of data to determine CFT uniquely. In addition to the scaling dimensions, structure factors, and central charge, a topological invariant has been found to be an important CFT datum to characterize and classify conformal field theories in one spatial dimension. Compared to the gapped topological phases, the topological properties of the conformal field theories are relatively less understood. In this talk, we present how quantum entanglement encodes the topological nature of conformal field theories. We studied a one-dimensional model of noninteracting fermions that realizes two Ising CFTs with different topological invariants. The logarithmic negativity, a computable entanglement measure of the mixed quantum states, can reveal the sharp signature of the quantum phase transitions between the two CFTs having the same central charge but different topological properties. We demonstrate that the quantized values of the negativity reveal which topological sectors the conformal field theories belong to. Furthermore, we examined finite temperature crossovers of the topological entanglement negativity, which can be a foundation for future experimental research. |
Thursday, March 9, 2023 9:36AM - 9:48AM |
S30.00009: Fermi edge singularity in neutral electron-hole plasma Darius J Choksy, Erik A Szwed, Leonid V Butov, Kirk W Baldwin, Loren N Pfeiffer We studied e-h systems created by optical excitation in separated electron and hole layers in GaAs/AlGaAs coupled quantum well heterostructure. The layer separation increases the e-h recombination time and, in turn, the density for a given optical excitation by orders of magnitude and, as a result, enables the realization of a dense and cold e-h system, with the density controlled by the excitation power. We found a strong enhancement of photoluminescence intensity at the Fermi energy of the neutral dense ultracold e-h plasma that evidences the emergence of excitonic Fermi edge singularity due to the Cooper-pair-like excitons at the Fermi energy. The photoluminescence lineshape and spontaneous coherence measurements show a crossover from BEC to BCS-like exciton condensate with increasing density, consistent with the theory predicting a smooth BEC - BCS transition. The Fermi edge singularity is the distinctive feature of the BCS-like exciton condensate. |
Thursday, March 9, 2023 9:48AM - 10:00AM |
S30.00010: Cascade of transitions in twisted and non-twisted graphene layers within the van Hove scenario Laura Classen, Dmitry Chichinadze, Yuxuan Wang, Andrey V Chubukov Motivated by measurements of compressibility and STM spectra in twisted bilayer graphene, we analyze the pattern of symmetry breaking for itinerant fermions near a van Hove singularity. Making use of an approximate SU(4) symmetry of the Landau functional, we show that the structure of the spin/isospin or- der parameter changes with increasing filling via a cascade of transitions. We compute the feedback from different spin/isospin orders on fermions and argue that each order splits the initially 4-fold degenerate van Hove peak in a particular fashion, consistent with the STM data and compressibility measurements, providing a unified interpretation of the cascade of transitions in twisted bilayer graphene. Our results follow from a generic analysis of an SU(4)-symmetric Landau functional and are valid beyond a specific underlying fermionic model. We argue that an analogous van Hove scenario explains the cascade of phase transitions in non-twisted Bernal bilayer and rhombohedral trilayer graphene. |
Thursday, March 9, 2023 10:00AM - 10:12AM |
S30.00011: Superconductor-Normal first order phase transition in the A15 phase of alkali-doped fullerides Theja DeSilva Using a recently developed effective model[1], we study the superconductor-normal phase transition of alkali-doped fullrides. First, we use a simple mean field theory to decouple the inverted Hund’s coupling term and the on-site repulsive term in the Hamiltonian. Then, by analyzing the Helmholtz free energy, we show that the superconductor-normal phase transition is a first order one. Second, we use a slave-rotor approach and a Hartree-Fock mean-field theory to investigate the normal phase where we find a Mott-insulating, a Fermi liquid metal, and a spin-density wave phases as a result of the competition between interacting term and the kinetic energy term in the effective Hamiltonian. Finally, we construct the global phase diagram of the body-centered cubic structured alkali-doped fullerides in the temperature-pressure parameter space. |
Thursday, March 9, 2023 10:12AM - 10:24AM |
S30.00012: Continuous Symmetry Breaking in a Trapped-Ion Crystal Lei Feng, Or Katz, Casey Haack, Andrew Risinger, Zhexuan Gong, Mohammad Maghrebi, Alexey V Gorshkov, Marko Cetina, Christopher Monroe One-dimensional systems can host quantum phases of matter with macroscopic order if the interaction range between the particles is sufficiently long. In most physical systems, however, the interactions are short-range, hindering the emergence of such phases in one dimension in general. Here we use a one-dimensional trapped-ion quantum simulator to prepare a many-body state in a Continuous Symmetry Breaking (CSB) phase with long-range spin order. Our preparation relies on simultaneous control over an array of 23 tightly focused individually addressing laser beams, generating long-range spin-spin interactions. We also observe a critical XY phase when the long-range interactions are frustrated. We further study the phases at different ranges of interaction and the out-of-equilibrium response to symmetry-breaking perturbations. This work opens an avenue to study new quantum phases and out-of-equilibrium dynamics in low-dimensional systems. |
Thursday, March 9, 2023 10:24AM - 10:36AM |
S30.00013: Transition from Kitaev quantum spin liquid to weakly coupled critical spin chains Shi Feng, Adhip Agarwala, Subhro Bhattacharjee, Nandini Trivedi We investigate quantum phase transitions in the Kitaev honeycomb model as a function of a magnetic field in the [001] direction and with bond anisotropy K_{z}/K with K_{x}=K_{y}=K. Using a combination of methods, exact diagonalization and density matrix renormalization group, and insights from mean field theory, we find four distinct phases as a function of (h,K_{z}/K): a gapless Kitaev spin liquid (KSL) at low anisotropy and low field, an intermediate gapless phase for a range of anisotropy K_{z}/K and h, the gapped Toric code phase at high anisotropy, and a trivial polarized phase. We show that the gapless to gapless transition between the KSL and the intermediate gapless phase is a Lifshitz transition driven by the change of occupation number of bond fermions. We further discover that the reduction of bond fermion occupation reduces the effective K_{z} coupling, resulting in weakly coupled chains that map to the critical Ising model in a transverse field. Approaching the intermediate gapless phase from high fields, linear spin wave theory performed in the polarized phase shows 1D boson modes dispersing only along the zigzag direction while having a flat band along the armchair direction. |
Thursday, March 9, 2023 10:36AM - 10:48AM |
S30.00014: Charge order and superconductivity in extended Hubbard models for AV3Sb5 kagome metals Francesco Ferrari, Morten Holm Christensen, Astrid T Rømer, Brian M Andersen, Federico Becca, Roser Valenti The Hubbard model on the kagome lattice is often considered as a minimal model to describe the rich low-temperature behavior of AV3Sb5 compounds (with A=K, Rb, Cs) [1], featuring charge-density waves (CDWs), superconductivity (SC), and possibly broken time-reversal symmetry. We investigate its ground-state properties when both onsite and nearest-neighbor Coulomb repulsions are considered at the van Hove filling. Our study is based on variational Jastrow-Slater wave functions which are capable of describing both CDW and SC phases and account for the effects of electronic correlation beyond the mean-field level. We reveal the presence of different repulsion-driven CDWs and, contrary to previous studies, the absence of ferromagnetism and charge- or spin-bond order. No signatures of chiral phases are detected. Remarkably, the CDWs triggered by the Coulomb repulsion possess charge disproportionations that are not compatible with the ones observed in AV3Sb5. As an alternative mechanism to stabilize charge order, we consider the electron-phonon interaction, modeled by coupling the hopping amplitudes to quantum phonons, as in the Su-Schrieffer-Heeger model. Our results show the instability towards a tri-hexagonal distortion with 2x2 periodicity, in a closer agreement with experimental findings [2]. |
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