Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session X22: Mott Physics Model Calculations |
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Sponsoring Units: DCMP Room: 321 |
Friday, March 18, 2016 8:00AM - 8:12AM |
X22.00001: Dimensional reduction in spin dynamics at Mott quantum criticality Jae-Ho Han, Yong-Heum Cho, Ki-Seok Kim One physical picture in describing metal-insulator transitions driven by strong interactions starts from a UV fixed point. Here, localized magnetic moments play the role of a source of strong inelastic scattering in Mott quantum criticality, which seems quite successful description at high temperature (e.g. anomalous scaling in electric resistivity). However, it has somewhat fundamental difficulty in explaining the low energy physics of a particular class of Mott insulators such as organic salts, where emergent localized magnetic moments are believed to form a spin liquid state. Here, starting from this spin-liquid IR fixed point, we investigate the Mott quantum criticality in (2$+$1) dimension (D). Our renormalization group analysis suggests that (2$+$1) D critical spin dynamics turns into (1$+$1) D dynamics, which originates from gauge invariance at Mott quantum criticality. Applying the bosonization framework, we find that critical spin dynamics is described by SU(2) k$=$1 Wess-Zumino-Witten theory in (1$+$1) D and critical charge dynamics is in the XY universality class of (2$+$1) D. We discuss speculations for the high temperature Mott quantum criticality based on this critical field theory. [Preview Abstract] |
Friday, March 18, 2016 8:12AM - 8:24AM |
X22.00002: Quasi-soliton scattering in quantum spin chains Davide Fioretto, Rogier Vljim, Martin Ganahl, Michael Brockmann, Masud Haque, Hans-Gerd Evertz, Jean-Sébastien Caux The quantum scattering of magnon bound states in the anisotropic Heisenberg spin chain is shown to display features similar to the scattering of solitons in classical exactly solvable models. Localized colliding Gaussian wave packets of bound magnons are constructed from string solutions of the Bethe equations and subsequently evolved in time, relying on an algebraic Bethe ansatz based framework for the computation of local expectation values in real space-time. The local magnetization profile shows the trajectories of colliding wave packets of bound magnons, which obtain a spatial displacement upon scattering. Analytic predictions on the displacements for various values of anisotropy and string lengths are derived from scattering theory and Bethe ansatz phase shifts, matching time evolution fits on the displacements. The TEBD algorithm allows for the study of scattering displacements from spin-block states, showing similar displacement scattering features. [Preview Abstract] |
Friday, March 18, 2016 8:24AM - 8:36AM |
X22.00003: Influence of spinons fluctuations near the spin liquid Mott transition Tsung-Han Lee, Serge Florens, Vladimir Dobrosavljevic We investigate the metal to Mott-insulator transition (MIT) in the Hubbard-Heisenberg model using the slave-rotor technique, which allows to combine for the first time the dynamical mean field theory (DMFT) with the Resonating Valence Bond (RVB) approach. In the spin-liquid phase at large Coulomb repulsion, the system shows a RVB transition from a trivial paramagnetic Mott insulator towards a low temperature insulating state with long lived spinons, as seen by the emergence of a linear specific heat. This quenching of the entropy in the spin liquid phase provides strong modifications in the shape of the standard DMFT phase diagram for the MIT occurring at intermediate values of the Coulomb repulsion. We find that the RVB transition happens concomitantly with the first order MIT lines at low temperature. This implies that the Mott insulator always accommodates a spinon Fermi surface, even in the coexistence regime of the MIT, and that the metallic state always stays a Fermi-liquid as it rejects the presence of free spinons, due to their strong scattering onto the holons. [Preview Abstract] |
Friday, March 18, 2016 8:36AM - 8:48AM |
X22.00004: Fractionalized Fermi liquids in a quantum dimer model Junhyun Lee, Steven White, Subir Sachdev We consider a quantum dimer model with bosonic and fermionic dimers, proposed to describe the pseudogap phase of cuprates. \footnote{Matthias Punk, Andrea Allais, and Subir Sachdev, Proc. Natl. Acad. Sci. USA \textbf{112}, 9552 (2015)} By density matrix renormalization group calculations on a finite cylinder, we obtain the ground state density distribution of the fermionic dimers for a number of different total densities. From the Friedel oscillations at open boundaries, we deduce that the Fermi surface consists of small hole pockets near $(\pi/2, \pi/2)$, and this feature persists up to 1/8 doping. Our results support the existence of a ``fractionalized Fermi liquid'' in this model. We also discuss the form factors of the density modulations. [Preview Abstract] |
Friday, March 18, 2016 8:48AM - 9:00AM |
X22.00005: Infinite bandwidth of a Mott-Hubbard insulator James Freericks, Jeffrey Cohn, Peter van Dongen, Hulikal Krishnamurthy The conventional viewpoint of the strongly correlated electron metal-insulator transition is that a single band splits into two upper and lower Hubbard bands at the metal-insulator transition. Much work has investigated whether this transition is continuous or discontinuous. Here we focus on another aspect and ask the question of whether there are additional upper and lower Hubbard bands, which stretch all the way out to infinity|leading to an infinite bandwidth for the Mott insulator. While we are not yet able to provide a rigorous proof of this result, we use exact diagonalization studies on small clusters to motivate the existence of these additional bands, and we discuss some different methods that might be utilized to provide a rigorous proof of this result. Even though the extra upper and lower Hubbard bands have very low total spectral weight, those states are expected to have extremely long lifetimes, leading to a nontrivial contribution to the transport density of states for dc transport and modifying the high temperature limit for the electrical resistivity. [Preview Abstract] |
Friday, March 18, 2016 9:00AM - 9:12AM |
X22.00006: Gaps, Pseudogaps, and the Nature of Charge in Holographic Fermion Models Garrett Vanacore, Philip Phillips Building on prior holographic constructions of Fermi arcs and Mott physics, we investigate the landscape of gapped and gapless strongly-correlated phases resulting from bulk fermion interactions in gauge/gravity duality. We test a proposed connection between bulk chiral symmetry and gapless boundary states, and discuss implications for discrete symmetry breaking in pseudogapped systems like the cuprate superconductors. Numerical methods are used to treat gravitational backreaction of bulk fermions, allowing more rigorous investigation of the existence of holographic Fermi surfaces and their adherence to Luttinger's rule. We use these techniques to study deviations from Luttinger's rule in holography, testing a recent claim that momentum-deconfined charges are at the heart of the Mott state. [Preview Abstract] |
Friday, March 18, 2016 9:12AM - 9:24AM |
X22.00007: Dimensional decoupling at continuous Mott transitions Liujun Zou, T Senthil For continuous Mott metal-insulator transitions in layered two dimensional systems, we demonstrate the phenomenon of dimensional decoupling: the system behaves as a three-dimensional metal in the Fermi liquid side but as a stack of decoupled two-dimensional layers in the Mott insulator. We show that the dimensional decoupling happens at the Mott quantum critical point itself. We derive the temperature dependence of the interlayer electric conductivity in various crossover regimes near such a continuous Mott transition, and discuss experimental implications. [Preview Abstract] |
Friday, March 18, 2016 9:24AM - 9:36AM |
X22.00008: Doping dependence of ordered phases in the Hubbard-Holstein model Christian Mendl, Elizabeth Nowadnick, Yvonne Kung, Brian Moritz, Steven Johnston, Thomas Devereaux Complex phase diagrams of strongly correlated materials are often accessed by the addition or removal of carriers, for example the emergence of high-temperature superconductivity from a charge transfer insulating state in the cuprates, and the metal-insulator transition in the nickelates. In many cases, these doping-dependent transitions are closely linked to the competition between multiple phases of similar energy scales, e.g., charge-stripe and superconducting states in the cuprates. The Hubbard-Holstein model, which includes electron-electron and electron-phonon interactions, provides a framework to study competing phases. In this talk I will present determinant quantum Monte Carlo (DQMC) simulations of the Hubbard-Holstein model and use spin and charge susceptibilities and single-particle spectral functions to elucidate the doping evolution of the competition between spin and charge order. [Preview Abstract] |
Friday, March 18, 2016 9:36AM - 9:48AM |
X22.00009: An electric field-driven MIT in strongly-correlated thin-film superlattices: an inhomogeneous dynamical mean-field theory study Petar Bakalov, Jean-Pierre Locquet Using an inhomogeneous dynamical mean-field theory (IDMFT) approach to the single-band Hubbard model we investigate the properties of thin-film superlattices made up of alternating strongly ($U_1$) and weakly ($U_2 < U_1$) correlated regions. In particular, we study the influence of temperature, doping, interaction strengths ($U_1, U_2$), superlattice parameters ($L_1, L_2$) and transverse electric field on the correlation driven Mott-Hubbard metal-to-insulator transition. We find that when the periodicity of the superlattice is such that the strongly correlated regions are below a certain thickness, the MIT is suppressed due to proximity effects. [Preview Abstract] |
Friday, March 18, 2016 9:48AM - 10:00AM |
X22.00010: Filament Formation and Electric-field-driven Resistive Switching in ordered Mott insulator Jiajun Li, Camille Aron, Gabriel Kotliar, Jong Han Formation of conductive filaments is widely observed in resistive switching experiments of strongly correlated materials. Although several theoretical scenarios have been suggested, the underlying mechanism is still far from completely understood within microscopic models. In this work, we study the spatial inhomogeneity during electric-field-driven AFI-to-PM transition in a dissipative Hubbard model\textsuperscript{1, 2}. We focus on the non-equilibrium steady state, by means of space-dependent Hartree-Fock approximation. It is shown that external field induces a first order insulator-to-metal transition (IMT) even when equilibrium transition is continuous. Disorder turns out to be crucial for formation of filaments. When impurities are placed in lattice, Joule heating assists to create robust conductive paths. Insulator-to-metal transition is then stimulated by conductive paths, with critical field significantly reduced.\\\\\par \noindent[1]J. E. Han and J. Li, Phys. Rev. B \textbf{88}, 075113 (2013)\par \noindent[2]J. Li, C. Aron, G. Kotliar, J. E. Han, Phys. Rev. Lett. \textbf{114}, 226403 (2015) [Preview Abstract] |
Friday, March 18, 2016 10:00AM - 10:12AM |
X22.00011: A Functional Renormalization Group Study of Hubbard Models with Correlated Hopping interactions. Nahom Yirga, Arianna Montorsi, David Campbell Hubbard Models with correlated hopping interactions have recently been derived from the Floquet Hamiltonian for driven Hubbard models [1]. We consider these models generalized to include an extended Hubbard interaction (V) and both with and without particle-hole symmetry. Using the Functional Renormalization Group method, we derive the phase diagram of this class of models in one and two dimensions. In one dimension we reproduce a spin transition to a bond-ordered phase previously seen in DMRG studies [2]. We extend these results to two dimensions. [1] M. Di Liberto, C. E. Creffield, G. I. Japaridze, C. Morais Smith, Phys. Rev. A 89, 013624 (2014) [2] A.A. Aligia et al., Phys. Rev. Lett. 99, 206401 (2007) [Preview Abstract] |
Friday, March 18, 2016 10:12AM - 10:24AM |
X22.00012: Quantum Monte Carlo study of bilayer ionic Hubbard model Mi Jiang The interaction-driven insulator-to-metal transition has been reported in the ionic Hubbard model (IHM) for intermediate interaction $U$, which poses fundamental interest in the correlated electronic systems. Here we use determinant quantum Monte Carlo to study the interplay of interlayer hybridization $V$ and two types of intralayer staggered potentials: one with the same (in-phase) and the other with a $\pi$-phase shift (anti-phase) potential in two layers termed as ``bilayer ionic Hubbard model''. We demonstrate that the interaction-driven Insulator-Metal transition extends to bilayer IHM with finite $V$ for both types of staggered potentials. Besides, the system with in-phase potential is prone to metallic phase with turning on interlayer hybridization while that with anti-phase potential tends to insulators with stronger charge density order. [Preview Abstract] |
Friday, March 18, 2016 10:24AM - 10:36AM |
X22.00013: Percolative Metal-Insulator transition in the doped Hubbard-Holstein model with the Gutzwiller Approach Jamshid Moradi Kurdestany, Sashi Satpathy Motivated by the recent progress in understanding of Mott insulators away from half filling, observed in many perovskite oxides, we study the metal-insulator transition in the Hubbard-Holstein model, which contains both the Coulomb and the electron-lattice (Jahn Teller) interactions by using the Gutzwiller variational method. We find that strong electron-lattice Interaction leads to phase separation, which however can be frustrated due to the long-range Coulomb interaction, resulting in a mixed phase consisting of puddles of metallic phases embedded in an insulating matrix. When the dopant concentration exceeds a threshold value $x_c$ , the metallic part forms a percolating network leading to metallic conduction. Depending on the strength of the electron-lattice interaction, $x_c$ can be of the order of 0.05 - 0.20 or so, which is the typical value observed in the perovskites. [Preview Abstract] |
Friday, March 18, 2016 10:36AM - 10:48AM |
X22.00014: Doping evolution of low-energy quasiparticles in the Hubbard model Brian Moritz, Yao Wang, Chunjing Jia, Yu He, Krzysztof Wohlfeld, Cheng-Chien Chen, Thomas P. Devereaux We investigate the single-particle spectra of the two-dimensional, single-band Hubbard model using cluster perturbation theory (CPT), paying considerable attention to low doping with a supercluster construction. At half-filling we find two distinct features: a spin polaron band due to strong coupling of a hole to magnons; and a second feature due to strongly renormalized, but effectively free, next-nearest neighbor hopping from additional delocalization pathways. With light hole-doping a third feature forms which disperses across the Fermi level, rapidly stealing spectral weight from the spin polaron. The doping evolution of this third feature is of particular importance as it constitutes the lowest energy degrees of freedom in the model. The three spectral features appear distinct, up to a relatively modest doping (12.5\%) where the spectral weight effectively has been exhausted in the spin polaron. We comment on the similarities, differences, and implications for the spectrum in doped cuprates and on competing interpretations of the spectral properties in the Hubbard model. [Preview Abstract] |
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