Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session F07: One and Two Dimensional Correlated Electron Systems |
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Sponsoring Units: DCMP Chair: Konstantin Matveev, Argonne National Laboratory Room: BCEC 109B |
Tuesday, March 5, 2019 11:15AM - 11:27AM |
F07.00001: Sound modes in one-dimensional quantum liquids Konstantin Matveev, Anton Andreev We study sound in one-dimensional Galilean invariant quantum liquids. In contrast to classical fluids, instead of a single sound mode we find a broad range of frequencies in which the system supports two sound modes. The nature of these modes depends on the type of particles forming the quantum liquid. In systems of spin-1/2 fermions, we find the first and second sound modes propagating at two different speeds. Similarly to superfluid 4He, the first sound is a wave of density, whereas the second one is a wave of entropy. In spinless quantum liquids we find two hybrid sound modes, which are simultaneous oscillations of both density and entropy, with relative phase shifts 0 or π. Their speeds are nearly equal, with the difference scaling linearly with the temperature. |
Tuesday, March 5, 2019 11:27AM - 11:39AM |
F07.00002: The fate of shock waves in quantum one-dimensional fluids at late times Thomas Veness, Leonid Glazman Classical hydrodynamics generically leads to the formation of shock waves which, at the most basic level, correspond to nonanalyticities in the fluid density as a function of spatial coordinates. |
Tuesday, March 5, 2019 11:39AM - 11:51AM |
F07.00003: Numerical evidence for continuous transition between Ising ferromagnet and valence bond solid in one dimension Brenden Roberts, Shenghan Jiang, Olexei I Motrunich We perform a numerical study of a spin-1/2 model with Z2 x Z2 symmetry in one dimension which demonstrates an interesting similarity to the physics of two-dimensional deconfined quantum critical points (DQCP). Specifically, we investigate the quantum phase transition between Ising ferromagnetic and valence bond solid (VBS) symmetry-breaking phases. Working directly in the thermodynamic limit using uniform matrix product states, we find evidence for a direct continuous phase transition which lies outside of the Landau-Ginzburg paradigm. In our model, the continuous transition is found everywhere on the phase boundary. We find that the magnetic and VBS correlations show identical power law exponent, which is expected from the self-duality of the parton description of this DQCP. Critical exponents vary continuously along the phase boundary and are in agreement with predictions of the field theory for this transition. We also find a regime where the phase boundary splits with the appearance of an intermediate phase of coexisting ferromagnetic and VBS order parameters, as suggested by the theory. |
Tuesday, March 5, 2019 11:51AM - 12:03PM |
F07.00004: Photoinduced enhancement of bond-order in the one-dimensional extended Hubbard model Can Shao, Takami Tohyama, Rubem Mondaini, Hong-Gang Luo, Hantao Lu Using the time-dependent Lanczos technique, we investigate the short-time evolution of the half-filled one-dimensional extended Hubbard model in the strong-coupling regime, when driven by a transient laser pulse. Starting from a phase displaying charge-density wave (CDW), a steady photoinduced in-gap state in the optical conductivity is found, depending on the parameters of the laser pulse. This potentially describes similar results of a recent experiment using organic salts [Nat. Phys. 7, 114 (2011)], also subjected to external drivings. On top of that, we parametrize the conditions of the pulse so as to maximize the overlap of the time-evolving wavefunction with excited states displaying the elusive bond-ordered wave of this model, with the focus on providing a protocol to experiments for its observation. Further, we try to make a connection between the emergence of this order and the formation of the aforementioned in-gap state, comparing with different types of excitations on the ground state. |
Tuesday, March 5, 2019 12:03PM - 12:15PM |
F07.00005: Competing orders in the one-dimensional Su-Schrieffer-Heeger model Manuel Weber, Martin Hohenadler We study the phase diagram of the one-dimensional spinless Su-Schrieffer-Heeger (SSH) model at half filling as a function of phonon frequency and electron-phonon coupling. In the adiabatic limit of static phonons (vanishing phonon frequency), the ground state is well understood to be a bond-ordered Peierls state that supports topological excitations at domain walls. In the antiadiabatic limit (infinite phonon frequency), the model maps onto the t-V model with a Luttinger liquid phase below and charge-density-wave order above a critical coupling. Using a recently developed directed-loop quantum Monte Carlo method for retarded interactions [1], we study the competition between these orders at finite phonon frequencies. |
Tuesday, March 5, 2019 12:15PM - 12:27PM |
F07.00006: Critical Entanglement for the Half-Filled One-Dimensional Extended Hubbard Model Jon Spalding, Shan-Wen Tsai, David K Campbell A fundamental problem in many-body physics is the characterization and classification of the ground states for materials involving strongly correlated electrons. For the Extended Hubbard Model at half-filling in one dimension, this has historically required challenging Quantum Monte Carlo or DMRG calculations for large system sizes in order to extract phase diagram information. Within the last two decades, advances in quantum information theory, and in particular, conformal field theory results for entanglement entropy scaling, have enabled unprecedented accuracy in computing critical properties of ground states. In this talk, we present new techniques based on conformal field theory that enable rapid, cheap extraction of critical points and critical exponents at both 2nd order and BKT transitions for open-boundary DMRG wave functions. The results of our study of the Extended Hubbard Model point to the broad applicability of the approach. |
Tuesday, March 5, 2019 12:27PM - 12:39PM |
F07.00007: Crossovers and critical scaling in the one-dimensional transverse-field Ising model Jianda Wu, Lijun Zhu, Qimiao Si We consider the scaling behavior of thermodynamic quantities in the one-dimensional transverse field |
Tuesday, March 5, 2019 12:39PM - 12:51PM |
F07.00008: Quantum field theory for the chiral clock transition in one spatial dimension Seth Whitsitt, Rhine Samajdar, Subir Sachdev We describe the quantum phase transition in the N-state chiral clock model in spatial dimension d=1. With particular couplings, such a model is in the universality class of recent experimental studies of the ordering of pumped Rydberg states in a one-dimensional chain of trapped ultracold alkali atoms. For N=3, the model is expected to have a direct phase transition from a gapped phase with a broken global Z_N symmetry, to a gapped phase with the Z_N symmetry restored. The transition has dynamical critical exponent z≠1, and so cannot be described by a relativistic quantum field theory. We map the transition onto that of a Bose gas in d=1, involving the onset of a single boson condensate in the background of a higher-dimensional N-boson condensate. We present a renormalization group analysis of the strongly coupled field theory for the Bose gas transition in an expansion in 2-d, with 4-N chosen to be of order 2-d. At two-loop order, we find a renormalization group fixed point which can describe a direct phase transition. |
Tuesday, March 5, 2019 12:51PM - 1:03PM |
F07.00009: Electrical Switching in Mott Material 1D Nanowires: Joule Heating vs. Electric Field Yoav Kalcheim, Javier del Valle, Min-Han Lee, Pavel Salev, Ivan Schuller We show unambiguous evidence for thermal and non-thermal mechanisms behind the insulator-to-metal transition in current-driven Mott materials. Distinguishing between these two mechanisms has proven difficult due to inhomogeneity of the current distribution in the device. By reducing the dimensionality of the devices to a one dimensional nanowire, inhomogeneity is avoided, thus allowing the two different mechanisms to be identified. The differences between the switching mechanisms in two prototypical Mott materials, VO2 and V2O3, are discussed. Our results have direct implications for applications in neuromorphic technologies. |
Tuesday, March 5, 2019 1:03PM - 1:15PM |
F07.00010: Coulomb-interaction-induced Majorana edge modes in nanowires Tommy Li, Karsten Flensberg, Michele Burrello It is shown that Majorana edge modes appear in a strongly correlated phase of semiconducting nanowires with discrete rotational symmetry in the cross section. These modes exist in the absence of spin-orbit coupling, magnetic fields and superconductivity. They appear purely due to the combination of the three-dimensional Coulomb interaction and orbital physics, which generates a fermionic condensate exhibiting a topological ground state degeneracy in a sector of the spectrum which is gapped to continuum modes. The gap can be comparable in magnitude to the topological superconducting gap in other solid-state candidate systems for Majorana edge modes, and may similarly be probed via tunnel spectroscopy. |
Tuesday, March 5, 2019 1:15PM - 1:27PM |
F07.00011: 1d Lattice Models for the Boundary of 2d “Majorana” Fermion SPTs: Kramers-Wannier Duality as an Exact Z2 Symmetry. Robert Jones, Max Metlitski A symmetry protected topological phase (SPT) is one which cannot be smoothly deformed into a trivial phase without breaking the symmetry. The symmetry which protects the phase acts "anomalously" on the edge of the SPT - for instance, in a non-onsite manner. Here, we examine the case when the anomaly is even more severe and the effective edge Hilbert space of the SPT does not admit a local tensor-product structure. |
Tuesday, March 5, 2019 1:27PM - 1:39PM |
F07.00012: Localization and Entanglement in Two-Dimensional Itinerant SYK Model Tze Tzen Ong We study a two dimensional itinerant SYK model with a linear dispersion, and by an asymptotic power series solution of the large-N saddle point equations, we find that the random SYK interactions result in formation of localized bound states. We will also discuss localization and entanglement phenomenon from calculating the density-density correlation function and the out-of-time-correlation function. |
Tuesday, March 5, 2019 1:39PM - 1:51PM |
F07.00013: Non-Linear transport in low density 2D hole systems Dmitrii Kruglov, Andrei Kogan, Chieh-Wen Liu, Xuan Gao, Loren Pfeiffer, Kenneth West We report measurements of non-linear magnetotransport in 10 nm wide p-doped GaAs/Al0.1Ga0.9As quantum wells with low hole density (n ~ 1010 cm-2) and high mobility (m ≈ 5 x 105 cm2/Vs). The Quantum Hall plateau-to-plateau transitions exhibit a universal dependence on bias voltage. We compare the results to theoretical predictions by assuming that the narrowing of the plateaus is caused by the temperature rise in the sample caused by the Joule heating. We find a good qualitative agreement with the predictions, but, surprisingly, the data show a stronger dependence on bias in the zero-bias limit than the theory suggests. We also discuss the high-frequency rectification spectroscopy as an approach for exploring dynamic effects in low-density hole systems and, in particular, the physics of insulating phases in two-dimensional transport at low carrier densities. |
Tuesday, March 5, 2019 1:51PM - 2:03PM |
F07.00014: Magnetoresistance at the 2D MIT: Evidence of Micro-emulsion Phases Shiqi Li, Qing Zhang, Pouyan Ghaemi, Myriam Sarachik Measurements of the in-plane magnetic field Bsat required to achieve full polarization of the electron spins in the strongly interacting two-dimensional electron system in a silicon MOSFET (Metal-Oxide-Semiconductor-Field-Effect Transistor) reveal the occurrence of a phase transition at a well-defined critical electron density for the metal-insulator transition determined from resistivity measurements. The behavior of Bsat as a function of electron density is consistent with the presence of a mixed, electronic micro-emulsion phase proposed by Spivak and Kivelson [1]. |
Tuesday, March 5, 2019 2:03PM - 2:15PM |
F07.00015: Phase diagrams of pi-flux quantum spin liquid in kagome lattice Hyeok-Jun Yang, SungBin Lee We study possible phase transitions between spin liquids and magnetically ordered states of quantum spin ice in a pyrochlore lattice. Focusing on a Kagome layer in the presence of [111] magnetic field, the modified ice rule enables the effective action to be expressed in the language of compact U(1) gauge theory. While Ising interaction defines the ground-state manifold, the spin-filp term is mapped to hopping of gauge charge after perturbation. In particular, for frustrated J, the gauge charge experiences pi-flux around the hexagon built from the triangular plaquette. Analyzing the action, the phase diagram is developed which exhibits U(1) spin liquid and out of this phase. We will also compare our results with previous relevant experiments and quantum |
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