1
|
Szabo JC, Lee K, Madhavan V, Trivedi N. Local Spectroscopies Reveal Percolative Metal in Disordered Mott Insulators. PHYSICAL REVIEW LETTERS 2020; 124:137402. [PMID: 32302164 DOI: 10.1103/physrevlett.124.137402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 06/11/2023]
Abstract
We elucidate the mechanism by which a Mott insulator transforms into a non-Fermi liquid metal upon increasing disorder at half filling. By correlating maps of the local density of states, the local magnetization, and the local bond conductivity, we find a collapse of the Mott gap toward a V-shaped pseudogapped density of states that occurs concomitantly with the decrease of magnetism around the highly disordered sites but an increase of bond conductivity. These metallic regions percolate to form an emergent non-Fermi liquid phase with a conductivity that increases with temperature. Bond conductivity measured via local microwave impedance combined with charge and spin local spectroscopies are ideal tools to corroborate our predictions.
Collapse
Affiliation(s)
- Joseph C Szabo
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Kyungmin Lee
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
| | - Vidya Madhavan
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Nandini Trivedi
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| |
Collapse
|
2
|
Schmehr JL, Mion TR, Porter Z, Aling M, Cao H, Upton MH, Islam Z, He RH, Sensarma R, Trivedi N, Wilson SD. Overdamped Antiferromagnetic Strange Metal State in Sr_{3}IrRuO_{7}. PHYSICAL REVIEW LETTERS 2019; 122:157201. [PMID: 31050510 DOI: 10.1103/physrevlett.122.157201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/24/2019] [Indexed: 06/09/2023]
Abstract
The unconventional electronic ground state of Sr_{3}IrRuO_{7} is explored via resonant x-ray scattering techniques and angle-resolved photoemission measurements. As the Ru content approaches x=0.5 in Sr_{3}(Ir_{1-x}Ru_{x})_{2}O_{7}, intermediate to the J_{eff}=1/2 Mott state in Sr_{3}Ir_{2}O_{7} and the quantum critical metal in Sr_{3}Ru_{2}O_{7}, a thermodynamically distinct metallic state emerges. The electronic structure of this intermediate phase lacks coherent quasiparticles, and charge transport exhibits a linear temperature dependence over a wide range of temperatures. Spin dynamics associated with the long-range antiferromagnetism of this phase show nearly local, overdamped magnetic excitations and an anomalously large energy scale of 200 meV-an energy far in excess of exchange energies present within either the Sr_{3}Ir_{2}O_{7} or Sr_{3}Ru_{2}O_{7} solid-solution end points. Overdamped quasiparticle dynamics driven by strong spin-charge coupling are proposed to explain the incoherent spectral features of the strange metal state in Sr_{3}IrRuO_{7}.
Collapse
Affiliation(s)
- Julian L Schmehr
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - Thomas R Mion
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Zach Porter
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - Michael Aling
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - Huibo Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Mary H Upton
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Zahirul Islam
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Rui-Hua He
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Rajdeep Sensarma
- Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Nandini Trivedi
- Mathematics Department, The Ohio State University, Columbus, Ohio 43210, USA
| | - Stephen D Wilson
- Materials Department, University of California, Santa Barbara, California 93106, USA
| |
Collapse
|
3
|
Wang Z, Okada Y, O'Neal J, Zhou W, Walkup D, Dhital C, Hogan T, Clancy P, Kim YJ, Hu YF, Santos LH, Wilson SD, Trivedi N, Madhavan V. Disorder induced power-law gaps in an insulator-metal Mott transition. Proc Natl Acad Sci U S A 2018; 115:11198-11202. [PMID: 30322914 PMCID: PMC6217382 DOI: 10.1073/pnas.1808056115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A correlated material in the vicinity of an insulator-metal transition (IMT) exhibits rich phenomenology and a variety of interesting phases. A common avenue to induce IMTs in Mott insulators is doping, which inevitably leads to disorder. While disorder is well known to create electronic inhomogeneity, recent theoretical studies have indicated that it may play an unexpected and much more profound role in controlling the properties of Mott systems. Theory predicts that disorder might play a role in driving a Mott insulator across an IMT, with the emergent metallic state hosting a power-law suppression of the density of states (with exponent close to 1; V-shaped gap) centered at the Fermi energy. Such V-shaped gaps have been observed in Mott systems, but their origins are as-yet unknown. To investigate this, we use scanning tunneling microscopy and spectroscopy to study isovalent Ru substitutions in Sr3(Ir1-xRux)2O7 (0 ≤ x ≤ 0.5) which drive the system into an antiferromagnetic, metallic state. Our experiments reveal that many core features of the IMT, such as power-law density of states, pinning of the Fermi energy with increasing disorder, and persistence of antiferromagnetism, can be understood as universal features of a disordered Mott system near an IMT and suggest that V-shaped gaps may be an inevitable consequence of disorder in doped Mott insulators.
Collapse
Affiliation(s)
- Zhenyu Wang
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL 61801
- Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801
| | - Yoshinori Okada
- Quantum Materials Science Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
| | - Jared O'Neal
- Mathematics Department, The Ohio State University, Columbus, OH 43210
| | - Wenwen Zhou
- Department of Physics, Boston College, Chestnut Hill, MA 02467
| | - Daniel Walkup
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Chetan Dhital
- Department of Physics, Kennesaw State University, Marietta, GA 30060
| | - Tom Hogan
- Materials Department, University of California, Santa Barbara, CA 93106
| | - Patrick Clancy
- Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
| | - Young-June Kim
- Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
| | - Y F Hu
- Canadian Light Source, Saskatoon, SK S7N 2V3, Canada
| | - Luiz H Santos
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL 61801
- Institute for Condensed Matter Theory, University of Illinois Urbana-Champaign, Urbana, IL 61801
| | - Stephen D Wilson
- Materials Department, University of California, Santa Barbara, CA 93106
| | - Nandini Trivedi
- Department of Physics, The Ohio State University, Columbus, Ohio 43210
| | - Vidya Madhavan
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL 61801;
- Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801
| |
Collapse
|
4
|
Patel ND, Mukherjee A, Kaushal N, Moreo A, Dagotto E. Non-Fermi Liquid Behavior and Continuously Tunable Resistivity Exponents in the Anderson-Hubbard Model at Finite Temperature. PHYSICAL REVIEW LETTERS 2017; 119:086601. [PMID: 28952753 DOI: 10.1103/physrevlett.119.086601] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Indexed: 06/07/2023]
Abstract
We employ a recently developed computational many-body technique to study for the first time the half-filled Anderson-Hubbard model at finite temperature and arbitrary correlation U and disorder V strengths. Interestingly, the narrow zero temperature metallic range induced by disorder from the Mott insulator expands with increasing temperature in a manner resembling a quantum critical point. Our study of the resistivity temperature scaling T^{α} for this metal reveals non-Fermi liquid characteristics. Moreover, a continuous dependence of α on U and V from linear to nearly quadratic is observed. We argue that these exotic results arise from a systematic change with U and V of the "effective" disorder, a combination of quenched disorder and intrinsic localized spins.
Collapse
Affiliation(s)
- Niravkumar D Patel
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Anamitra Mukherjee
- School of Physical Sciences, National Institute of Science Education and Research, HBNI, Jatni 752050, India
| | - Nitin Kaushal
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Adriana Moreo
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Elbio Dagotto
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| |
Collapse
|
5
|
Ma L, Ye C, Yu Y, Lu XF, Niu X, Kim S, Feng D, Tománek D, Son YW, Chen XH, Zhang Y. A metallic mosaic phase and the origin of Mott-insulating state in 1T-TaS2. Nat Commun 2016; 7:10956. [PMID: 26961788 PMCID: PMC4792954 DOI: 10.1038/ncomms10956] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Accepted: 02/04/2016] [Indexed: 11/20/2022] Open
Abstract
Electron–electron and electron–phonon interactions are two major driving forces that stabilize various charge-ordered phases of matter. In layered compound 1T-TaS2, the intricate interplay between the two generates a Mott-insulating ground state with a peculiar charge-density-wave (CDW) order. The delicate balance also makes it possible to use external perturbations to create and manipulate novel phases in this material. Here, we study a mosaic CDW phase induced by voltage pulses, and find that the new phase exhibits electronic structures entirely different from that of the original Mott ground state. The mosaic phase consists of nanometre-sized domains characterized by well-defined phase shifts of the CDW order parameter in the topmost layer, and by altered stacking relative to the layers underneath. We discover that the nature of the new phase is dictated by the stacking order, and our results shed fresh light on the origin of the Mott phase in 1T-TaS2. In correlated materials, new phases emerge when the balance between many-body interactions is perturbed. Here, Ma et al. induce a mosaic charge-density-wave phase out of Mott insulating state in layered 1T-TaS2 by voltage pulses, which reveals a dominating role of interlayer stacking order.
Collapse
Affiliation(s)
- Liguo Ma
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Cun Ye
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Yijun Yu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Xiu Fang Lu
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.,Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.,Key Laboratory of Strongly Coupled Quantum Matter Physics, Chinese Academy of Sciences, School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Xiaohai Niu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Sejoong Kim
- Korea Institute for Advanced Study, Hoegiro 85, Seoul 02455, Korea
| | - Donglai Feng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - David Tománek
- Physics and Astronomy Department, Michigan State University, East Lansing, Michigan 48824, USA
| | - Young-Woo Son
- Korea Institute for Advanced Study, Hoegiro 85, Seoul 02455, Korea
| | - Xian Hui Chen
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.,Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.,Key Laboratory of Strongly Coupled Quantum Matter Physics, Chinese Academy of Sciences, School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Yuanbo Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| |
Collapse
|
6
|
Nanoscale manipulation of the Mott insulating state coupled to charge order in 1T-TaS2. Nat Commun 2016; 7:10453. [PMID: 26795073 PMCID: PMC4735893 DOI: 10.1038/ncomms10453] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 12/10/2015] [Indexed: 11/08/2022] Open
Abstract
The controllability over strongly correlated electronic states promises unique electronic devices. A recent example is an optically induced ultrafast switching device based on the transition between the correlated Mott insulating state and a metallic state of a transition metal dichalcogenide 1T-TaS2. However, the electronic switching has been challenging and the nature of the transition has been veiled. Here we demonstrate the nanoscale electronic manipulation of the Mott state of 1T-TaS2. The voltage pulse from a scanning tunnelling microscope switches the insulating phase locally into a metallic phase with irregularly textured domain walls in the charge density wave order inherent to this Mott state. The metallic state is revealed as a correlated phase, which is induced by the moderate reduction of electron correlation due to the charge density wave decoherence.
Collapse
|
7
|
Javan Mard H, Andrade EC, Miranda E, Dobrosavljević V. Non-Gaussian spatial correlations dramatically weaken localization. PHYSICAL REVIEW LETTERS 2015; 114:056401. [PMID: 25699458 DOI: 10.1103/physrevlett.114.056401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Indexed: 06/04/2023]
Abstract
We perform variational studies of the interaction-localization problem to describe the interaction-induced renormalizations of the effective (screened) random potential seen by quasiparticles. Here we present results of careful finite-size scaling studies for the conductance of disordered Hubbard chains at half-filling and zero temperature. While our results indicate that quasiparticle wave functions remain exponentially localized even in the presence of moderate to strong repulsive interactions, we show that interactions produce a strong decrease of the characteristic conductance scale g^{*} signaling the crossover to strong localization. This effect, which cannot be captured by a simple renormalization of the disorder strength, instead reflects a peculiar non-Gaussian form of the spatial correlations of the screened disordered potential, a hitherto neglected mechanism to dramatically reduce the impact of Anderson localization (interference) effects.
Collapse
Affiliation(s)
- H Javan Mard
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
| | - E C Andrade
- Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany
| | - E Miranda
- Instituto de Física Gleb Wataghin, Unicamp, R. Sérgio Buarque de Holanda, 777, Campinas, SP 13083-859, Brazil
| | - V Dobrosavljević
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
| |
Collapse
|
8
|
Dhital C, Hogan T, Zhou W, Chen X, Ren Z, Pokharel M, Okada Y, Heine M, Tian W, Yamani Z, Opeil C, Helton JS, Lynn JW, Wang Z, Madhavan V, Wilson SD. Carrier localization and electronic phase separation in a doped spin-orbit-driven Mott phase in Sr₃(Ir(1-x)Ru(x))₂O₇. Nat Commun 2014; 5:3377. [PMID: 24566714 DOI: 10.1038/ncomms4377] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 02/04/2014] [Indexed: 11/09/2022] Open
Abstract
Interest in many strongly spin-orbit-coupled 5d-transition metal oxide insulators stems from mapping their electronic structures to a J(eff)=1/2 Mott phase. One of the hopes is to establish their Mott parent states and explore these systems' potential of realizing novel electronic states upon carrier doping. However, once doped, little is understood regarding the role of their reduced Coulomb interaction U relative to their strongly correlated 3d-electron cousins. Here we show that, upon hole-doping a candidate J(eff)=1/2 Mott insulator, carriers remain localized within a nanoscale phase-separated ground state. A percolative metal-insulator transition occurs with interplay between localized and itinerant regions, stabilizing an antiferromagnetic metallic phase beyond the critical region. Our results demonstrate a surprising parallel between doped 5d- and 3d-electron Mott systems and suggest either through the near-degeneracy of nearby electronic phases or direct carrier localization that U is essential to the carrier response of this doped spin-orbit Mott insulator.
Collapse
Affiliation(s)
- Chetan Dhital
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Tom Hogan
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Wenwen Zhou
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Xiang Chen
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Zhensong Ren
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Mani Pokharel
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Yoshinori Okada
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - M Heine
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Wei Tian
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA
| | - Z Yamani
- Chalk River Laboratories, Canadian Neutron Beam Centre, National Research Council, Chalk River, Ontario, Canada K0J 1P0
| | - C Opeil
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - J S Helton
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
| | - J W Lynn
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
| | - Ziqiang Wang
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Vidya Madhavan
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Stephen D Wilson
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| |
Collapse
|
9
|
Gadway B, Pertot D, Reeves J, Vogt M, Schneble D. Glassy behavior in a binary atomic mixture. PHYSICAL REVIEW LETTERS 2011; 107:145306. [PMID: 22107210 DOI: 10.1103/physrevlett.107.145306] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 08/14/2011] [Indexed: 05/31/2023]
Abstract
We experimentally study one-dimensional, lattice-modulated Bose gases in the presence of an uncorrelated disorder potential formed by localized impurity atoms, and compare to the case of correlated quasidisorder formed by an incommensurate lattice. While the effects of the two disorder realizations are comparable deeply in the strongly interacting regime, both showing signatures of Bose-glass formation, we find a dramatic difference near the superfluid-to-insulator transition. In this transition region, we observe that random, uncorrelated disorder leads to a shift of the critical lattice depth for the breakdown of transport as opposed to the case of correlated quasidisorder, where no such shift is seen. Our findings, which are consistent with recent predictions for interacting bosons in one dimension, illustrate the important role of correlations in disordered atomic systems.
Collapse
Affiliation(s)
- Bryce Gadway
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA.
| | | | | | | | | |
Collapse
|
10
|
Haverkamp RG, Marshall AT, Cowie BCC. Energy resolved XPS depth profile of (IrO2
, RuO2
, Sb2
O5
, SnO2
) electrocatalyst powder to reveal core-shell nanoparticle structure. SURF INTERFACE ANAL 2011. [DOI: 10.1002/sia.3644] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
11
|
Song Y, Bulut S, Wortis R, Atkinson WA. Effects of strong correlations on the disorder-induced zero-bias anomaly in the extended Anderson-Hubbard model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:385601. [PMID: 21832373 DOI: 10.1088/0953-8984/21/38/385601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We study the effect of strong correlations on the zero-bias anomaly (ZBA) in disordered interacting systems. We focus on the two-dimensional extended Anderson-Hubbard model (EAHM) on a square lattice. The EAHM has both on-site and nearest-neighbour interactions and randomly chosen site energies. We use a mean-field theory that incorporates strong correlations and treats the disorder potential exactly. We use a simplified atomic-limit approximation for the diagonal inelastic self-energy that becomes exact in the large-disorder limit, and the off-diagonal self-energy is treated within the Hartree-Fock approximation. The validity of these approximations is discussed in detail. We find that strong correlations have a significant effect on the ZBA at half-filling, and enhance the ZBA gap when the interaction is finite ranged.
Collapse
Affiliation(s)
- Yun Song
- Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | | | | | | |
Collapse
|
12
|
Meneghini C, Ray S, Liscio F, Bardelli F, Mobilio S, Sarma DD. Nature of "disorder" in the ordered double perovskite Sr2FeMoO6. PHYSICAL REVIEW LETTERS 2009; 103:046403. [PMID: 19659376 DOI: 10.1103/physrevlett.103.046403] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Indexed: 05/13/2023]
Abstract
The degree of B/B;{'} alternate cation order is known to heavily influence the magnetic properties of A_{2}BB;{'}O_{6} double perovskites although the nature of such disorder has never been critically studied. Our detailed x-ray absorption fine structure studies in conjunction with synchrotron radiation x-ray diffraction experiments on polycrystalline Sr_{2}FeMoO_{6} samples with various degrees of disorder reveal that a very high degree of short range order is preserved even in samples with highly reduced long range chemical order. Based on these experimental results and with the help of detailed structural simulations, we are able to model the nature of the disorder in this important class of materials and discuss the consequent implications on its physical properties.
Collapse
Affiliation(s)
- C Meneghini
- Dipartimento di Fisica, Universitá di Roma Tre, I-00146 Roma, Italy
| | | | | | | | | | | |
Collapse
|
13
|
Byczuk K, Hofstetter W, Vollhardt D. Competition between Anderson localization and antiferromagnetism in correlated lattice fermion systems with disorder. PHYSICAL REVIEW LETTERS 2009; 102:146403. [PMID: 19392461 DOI: 10.1103/physrevlett.102.146403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Indexed: 05/27/2023]
Abstract
The magnetic ground state phase diagram of the disordered Hubbard model at half-filling is computed in dynamical mean-field theory supplemented with the spin resolved, typical local density of states. The competition between many-body correlations and disorder is found to stabilize paramagnetic and antiferromagnetic metallic phases at weak interactions. Strong disorder leads to Anderson localization of the electrons and suppresses the antiferromagnetic long-range order. Slater and Heisenberg antiferromagnets respond characteristically differently to disorder. The results can be tested with cold fermionic atoms loaded into optical lattices.
Collapse
Affiliation(s)
- Krzysztof Byczuk
- Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute for Physics, University of Augsburg, D-86135 Augsburg, Germany
| | | | | |
Collapse
|
14
|
Shinaoka H, Imada M. Soft hubbard gaps in disordered itinerant models with short-range interaction. PHYSICAL REVIEW LETTERS 2009; 102:016404. [PMID: 19257220 DOI: 10.1103/physrevlett.102.016404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Indexed: 05/27/2023]
Abstract
We study the Anderson-Hubbard model in the Hartree-Fock approximation and the exact diagonalization under the coexistence of short-range interaction and diagonal disorder. We show that there exist unconventional soft gaps, where the single-particle (SP) density of states (DOS) A follows a scaling in energy E as A(E) proportional, variantexp[-(-gammalog|E-E_{F}|);{d}] irrespective of electron filling and long-range order. Here, d is the spatial dimension, E_{F} the Fermi energy and gamma a nonuniversal constant. We propose a multivalley energy landscape as their origin. Possible experiments to verify the present theory are proposed.
Collapse
Affiliation(s)
- Hiroshi Shinaoka
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | | |
Collapse
|
15
|
Fazileh F, Gooding RJ, Atkinson WA, Johnston DC. Role of strong electronic correlations in the metal-to-insulator transition in disordered LiAlyTi2-yO4. PHYSICAL REVIEW LETTERS 2006; 96:046410. [PMID: 16486863 DOI: 10.1103/physrevlett.96.046410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Indexed: 05/06/2023]
Abstract
The compound LiAlyTi2-yO4 undergoes a metal-to-insulator transition for yc approximately 0.33. It is known that disorder alone is insufficient to explain this transition; e.g., a quantum site percolation model predicts yc approximately 0.8. We have included (Hubbard) electronic interactions into a model of this compound, using a real-space Hartree-Fock approach that achieves self-consistency at every site, and have found that for a Hubbard energy equal to 1.5 times the non-interacting bandwidth one obtains yc approximately 0.3. Further, with increasing Hubbard energy we find an Altshuler-Aronov suppression of the density of states, deltaN(epsilon) approximately square root /epsilon-epsilonF/, that reduces the density of states at the Fermi energy to zero at the critical Hubbard interaction. Using this ratio of correlation to hopping energy one is led to a prediction of the near-neighbor superexchange (J/t approximately 1/3) which is similar to that for the cuprate superconductors.
Collapse
Affiliation(s)
- F Fazileh
- Department of Physics, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | | | | | | |
Collapse
|