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Kagalovsky V, Kravchenko SV, Nemirovsky D. Quantum scaling for the metal-insulator transition in a two-dimensional electron system. Sci Rep 2024; 14:12584. [PMID: 38822032 PMCID: PMC11143205 DOI: 10.1038/s41598-024-63221-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 05/27/2024] [Indexed: 06/02/2024] Open
Abstract
The quantum phase transition observed experimentally in two-dimensional (2D) electron systems has been a subject of theoretical and experimental studies for almost 30 years. We suggest Gaussian approximation to the mean-field theory of the second-order phase transition to explain the experimental data. Our approach explains self-consistently the universal value of the critical exponent 3/2 (found after scaling measured resistivities on both sides of the transition as a function of temperature) as the result of the divergence of the correlation length when the electron density approaches the critical value. We also provide numerical evidence for the stretched exponential temperature dependence of the metallic phase's resistivities in a wide range of temperatures and show that it leads to correct qualitative results. Finally, we interpret the phase diagram on the density-temperature plane exhibiting the quantum critical point, quantum critical trajectory and two crossover lines. Our research presents a theoretical description of the seminal experimental results.
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Affiliation(s)
- V Kagalovsky
- Shamoon College of Engineering, 84105, Beer-Sheva, Israel
| | - S V Kravchenko
- Department of Physics, Northeastern University, Boston, MA, 02115, USA.
| | - D Nemirovsky
- Shamoon College of Engineering, 84105, Beer-Sheva, Israel
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2
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Ali N, Singh B, Srivastava PK, Ali F, Lee M, Park H, Shin H, Lee K, Choi H, Lee S, Ngo TD, Hassan Y, Watanabe K, Taniguchi T, Lee C, Yoo WJ. Link between T-Linear Resistivity and Quantum Criticality in Ambipolar Black Phosphorus. ACS NANO 2024; 18:11978-11987. [PMID: 38652759 DOI: 10.1021/acsnano.4c02432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
The interplay between strong Coulomb interactions and kinetic energy leads to intricate many-body competing ground states owing to quantum fluctuations in 2D electron and hole gases. However, the simultaneous observation of quantum critical phenomena in both electron and hole regimes remains elusive. Here, we utilize anisotropic black phosphorus (BP) to show density-driven metal-insulator transition with a critical conductance ∼e2/h which highlights the significant role of quantum fluctuations in both hole and electron regimes. We observe a T-linear resistivity from the deep metallic phase to the metal-insulator boundary at moderate temperatures, while it turns to Fermi liquid behavior in the deep metallic phase at low temperatures in both regimes. An analysis of the resistivity suggests that disorder-dominated transport leads to T-linear behavior in the hole regime, while in the electron regime, the T-linear resistivity results from strong Coulomb interactions, suggestive of strange-metal behavior. Successful scaling collapse of the resistivity in the T-linear region demonstrates the link between quantum criticality and the T-linear resistivity in both regimes. Our study provides compelling evidence that ambipolar BP could serve as an exciting testbed for investigating exotic states and quantum critical phenomena in hole and electron regimes of 2D semiconductors.
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Affiliation(s)
- Nasir Ali
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Budhi Singh
- School of Mechanical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Pawan Kumar Srivastava
- School of Mechanical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Fida Ali
- Department of Electronic and Nanoengineering, Aalto University, P.O. Box 13500, Aalto FI-00076, Finland
| | - Myeongjin Lee
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Hyokwang Park
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Hoseong Shin
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Kwangro Lee
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Hyungyu Choi
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Sungwon Lee
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Tien Dat Ngo
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Yasir Hassan
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Changgu Lee
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
- School of Mechanical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
| | - Won Jong Yoo
- SKKU Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea
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3
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Takahashi K, Nakatsugawa K, Sakoda M, Nanao Y, Nobukane H, Obuse H, Tanda S. Bose glass and Fermi glass. Sci Rep 2023; 13:12434. [PMID: 37528223 PMCID: PMC10394042 DOI: 10.1038/s41598-023-39285-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 07/22/2023] [Indexed: 08/03/2023] Open
Abstract
It is known that two-dimensional superconducting materials undergo a quantum phase transition from a localized state to superconductivity. When the disordered samples are cooled, bosons (Cooper pairs) are generated from Fermi glass and reach superconductivity through Bose glass. However, there has been no universal expression representing the transition from Fermi glass to Bose glass. Here, we discovered an experimental renormalization group flow from Fermi glass to Bose glass in terms of simple [Formula: see text]-function analysis. To discuss the universality of this flow, we analyzed manifestly different systems, namely a Nd-based two-dimensional layered perovskite and an ultrathin Pb film. We find that all our experimental data for Fermi glass fall beautifully into the conventional self-consistent [Formula: see text]-function. Surprisingly, however, flows perpendicular to the conventional [Formula: see text]-function are observed in the weakly localized regime of both systems, where localization becomes even weaker. Consequently, we propose a universal transition from Bose glass to Fermi glass with the new two-dimensional critical sheet resistance close to [Formula: see text].
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Affiliation(s)
- Korekiyo Takahashi
- Department of Applied Physics, Hokkaido University, Sapporo, 060-8628, Japan.
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan.
- Nomura Research Institute, Ltd., Tokyo, 100-0004, Japan.
| | - Keiji Nakatsugawa
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan
- Research Center for Materials Nanoarchitectonics, National Institute for Material Science, Tsukuba, 305-0044, Japan
| | - Masahito Sakoda
- Department of Applied Physics, Hokkaido University, Sapporo, 060-8628, Japan
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan
| | - Yoshiko Nanao
- School of Physics and Astronomy, University of St Andrews, Fife, KY16 9SS, Scotland
| | - Hiroyoshi Nobukane
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan
| | - Hideaki Obuse
- Department of Applied Physics, Hokkaido University, Sapporo, 060-8628, Japan
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan
| | - Satoshi Tanda
- Department of Applied Physics, Hokkaido University, Sapporo, 060-8628, Japan
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan
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4
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Falson J, Sodemann I, Skinner B, Tabrea D, Kozuka Y, Tsukazaki A, Kawasaki M, von Klitzing K, Smet JH. Competing correlated states around the zero-field Wigner crystallization transition of electrons in two dimensions. NATURE MATERIALS 2022; 21:311-316. [PMID: 34949813 DOI: 10.1038/s41563-021-01166-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 11/04/2021] [Indexed: 06/14/2023]
Abstract
The competition between kinetic energy and Coulomb interactions in electronic systems leads to complex many-body ground states with competing orders. Here we present zinc oxide-based two-dimensional electron systems as a high-mobility system to study the low-temperature phases of strongly interacting electrons. An analysis of the electronic transport provides evidence for competing correlated metallic and insulating states with varying degrees of spin polarization. Some features bear quantitative resemblance to quantum Monte Carlo simulation results, including the transition point from the paramagnetic Fermi liquid to Wigner crystal and the absence of a Stoner transition. At very low temperatures, we resolve a non-monotonic spin polarizability of electrons across the phase transition, pointing towards a low spin phase of electrons, and a two-order-of-magnitude positive magnetoresistance that is challenging to understand within traditional metallic transport paradigms. This work establishes zinc oxide as a platform for studying strongly correlated electrons in two dimensions.
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Affiliation(s)
- J Falson
- Max-Planck-Institute for Solid State Research, Stuttgart, Germany.
- Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA, USA.
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA, USA.
| | - I Sodemann
- Institut für Theoretische Physik, Universität Leipzig, Leipzig, Germany
- Max-Planck-Institute for the Physics of Complex Systems, Dresden, Germany
| | - B Skinner
- Department of Physics, Ohio State University, Columbus, OH, USA
| | - D Tabrea
- Max-Planck-Institute for Solid State Research, Stuttgart, Germany
| | - Y Kozuka
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, Tsukuba, Japan
- PRESTO, JST, Kawaguchi, Japan
| | - A Tsukazaki
- Institute for Materials Research, Tohoku University, Sendai, Japan
| | - M Kawasaki
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - K von Klitzing
- Max-Planck-Institute for Solid State Research, Stuttgart, Germany
| | - J H Smet
- Max-Planck-Institute for Solid State Research, Stuttgart, Germany
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5
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Zhao PL, Lu HZ, Xie XC. Theory for Magnetic-Field-Driven 3D Metal-Insulator Transitions in the Quantum Limit. PHYSICAL REVIEW LETTERS 2021; 127:046602. [PMID: 34355953 DOI: 10.1103/physrevlett.127.046602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/07/2021] [Accepted: 06/17/2021] [Indexed: 06/13/2023]
Abstract
Metal-insulator transitions driven by magnetic fields have been extensively studied in 2D, but a 3D theory is still lacking. Motivated by recent experiments, we develop a scaling theory for the metal-insulator transitions in the strong-magnetic-field quantum limit of a 3D system. By using a renormalization-group calculation to treat electron-electron interactions, electron-phonon interactions, and disorder on the same footing, we obtain the critical exponent that characterizes the scaling relations of the resistivity to temperature and magnetic field. By comparing the critical exponent with those in a recent experiment [F. Tang et al., Nature (London) 569, 537 (2019)NATUAS0028-083610.1038/s41586-019-1180-9], we conclude that the insulating ground state was not only a charge-density wave driven by electron-phonon interactions but also coexisting with strong electron-electron interactions and backscattering disorder. We also propose a current-scaling experiment for further verification. Our theory will be helpful for exploring the emergent territory of 3D metal-insulator transitions under strong magnetic fields.
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Affiliation(s)
- Peng-Lu Zhao
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Hai-Zhou Lu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - X C Xie
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing Academy of Quantum Information Sciences, West Building 3, No. 10, Xibeiwang East Road, Haidian District, Beijing 100193, China
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6
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Danilyuk AL, Prischepa SL, Trafimenko AG, Fedotov AK, Svito IA, Kargin NI. Low temperature injected-caused charge carrier instability in n-type silicon below insulator-to-metal transition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:225702. [PMID: 32005031 DOI: 10.1088/1361-648x/ab720e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report on the electric transport properties of Si heavily doped with Sb at concentration just below the insulator-to-metal transition in the temperature range 1.9-3.0 K for current density J < 0.2 A cm-2. The change in the sign of the temperature dependence of the differential resistivity [Formula: see text] was observed: the d[Formula: see text]/dT is positive if J < 0.045 A cm-2 whereas it becomes negative at J > 0.045 A cm-2. The effect is explained assuming the exchange by electrons between the upper Hubbard band (UHB) and the conduction band. The obtained J dependencies of the activation energy, nonequilibrium concentration, mobility and scattering time of the conduction electrons correspond well to this hypothesis. The reason for charge instability is the Coulomb repulsion between electrons occupying states both in the UHB and conduction band. The estimated J dependencies of the conduction electrons lifetime and concentration of the D- states in the UHB strongly supports this assumption.
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Affiliation(s)
- A L Danilyuk
- Belarusian State University of Informatics and Radioelectronics, P. Browka 6, Minsk, 220013, Belarus
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7
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Patil PD, Ghosh S, Wasala M, Lei S, Vajtai R, Ajayan PM, Ghosh A, Talapatra S. Gate-Induced Metal-Insulator Transition in 2D van der Waals Layers of Copper Indium Selenide Based Field-Effect Transistors. ACS NANO 2019; 13:13413-13420. [PMID: 31661261 DOI: 10.1021/acsnano.9b06846] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The existence of an exquisite phenomenon such as a metal-insulator transition (MIT) in two-dimensional (2D) systems, where completely different electronic functionalities in the same system can emerge simply by regulating parameters such as charge carrier density in them, is noteworthy. Such tunability in material properties can lead to several applications where precise tuning of function specific properties are desirable. Here, we report on our observation on the occurrence of MIT in the 2D material system of copper indium selenide (CuIn7Se11). Clear evidence of the metallic nature of conductivity (σ) under the influence of electrostatic doping via the gate, which crosses over to an insulating phase upon lowering the temperature, was observed by investigating the temperature and gate dependence of σ in CuIn7Se11 field-effect transistor devices. At higher charge carrier densities (n > 1012 cm-1), we found that σ ∼ (n)α with α ∼ 2, which suggests the presence of bare Coulomb impurity scattering within the studied range of temperature (280 K > T > 20 K). Our analysis of the conductivity data following the principles of percolation theory of transition where σ ∼ (n - nC)δ show that the critical percolation exponent δ(T) has average values ∼1.57 ± 0.27 and 1.02 ± 0.35 within the measured temperature range for the two devices and it is close to the 2D percolation exponent value of 1.33. We believe that the 2D MIT seen in our system is due to the charge density inhomogeneity caused by electrostatic doping and unscreened charge impurity scattering that leads to a percolation driven transition. The findings reported here for CuIn7Se11 system provide a different material platform to investigate MIT in 2D and are crucial in order to understand the fundamental basis of electronic interactions and charge-transport phenomenon in other unexplored 2D electron systems.
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Affiliation(s)
- Prasanna D Patil
- Department of Physics , Southern Illinois University Carbondale , Carbondale , Illinois 62901 , United States
| | - Sujoy Ghosh
- Department of Physics , Southern Illinois University Carbondale , Carbondale , Illinois 62901 , United States
| | - Milinda Wasala
- Department of Physics , Southern Illinois University Carbondale , Carbondale , Illinois 62901 , United States
| | - Sidong Lei
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
- Department of Physics and Astronomy , Georgia State University , Atlanta , Georgia 30303 , United States
| | - Robert Vajtai
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
| | - Pulickel M Ajayan
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
| | - Arindam Ghosh
- Department of Physics , Indian Institute of Science , Bangalore 560012 , India
- Centre for Nano Science and Engineering , Indian Institute of Science , Bangalore 560012 , India
| | - Saikat Talapatra
- Department of Physics , Southern Illinois University Carbondale , Carbondale , Illinois 62901 , United States
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Moon BH, Bae JJ, Han GH, Kim H, Choi H, Lee YH. Anomalous Conductance near Percolative Metal-Insulator Transition in Monolayer MoS 2 at Low Voltage Regime. ACS NANO 2019; 13:6631-6637. [PMID: 31122017 DOI: 10.1021/acsnano.9b00755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Conductivity of the insulating phase increases generally at an elevated drain-source voltage due to the field-enhanced hopping or heating effect. Meanwhile, a transport mechanism governed by percolation in a low compensated semiconductor gives rise to the reduced conductivity at a low-field regime. Here, in addition to this behavior, we report the anomalous conductivity behavior to transform from a percolative metallic to an insulating phase at the low voltage regime in monolayer molybdenum disulfide (MoS2). Percolation transport at low source-drain voltage is governed by inhomogeneously distributed potential in strongly interacting monolayer MoS2 with a substrate, distinct from the quantum phase transition in multilayer MoS2. At a high source-drain voltage regime, the insulating phase is transformed further to a metallic phase, exhibiting multiphases of metallic-insulating-metallic transitions in monolayer MoS2. These behaviors highlight MoS2 as a model system to study various classical and quantum transports as well as metal-insulator transition in two-dimensional systems.
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Affiliation(s)
- Byoung Hee Moon
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Jung Jun Bae
- WIT Co., Ltd. , 89, Seoho-ro, Gwonseon-gu , Suwon 16614 , Republic of Korea
| | - Gang Hee Han
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
| | - Hyun Kim
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Homin Choi
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics , Institute for Basic Science (IBS) , Suwon 16419 , Republic of Korea
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
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9
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Localization Parameters for Two Interacting Particles in Disordered Two-Dimensional Finite Lattices. CONDENSED MATTER 2018. [DOI: 10.3390/condmat3040038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
I study spreading of two interacting hardcore bosons in disordered two-dimensional finite lattices from an initial occupation of two adjacent sites. The parameters related to the spreading of the particles provide an insight on the effect of interaction. I find that the presence of interaction makes the particles less localized than the non-interacting ones within the range of disorder strength W ≤ 4 and interaction strength V ≤ 4 . If the interaction strength is higher, then particles localize more. A transition with changes in the character of dominant correlations is found at critical disorder strengths for each chosen strength of interaction. The nature of correlations between the particles as nearest neighbours becomes dominant beyond these disorder strengths.
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10
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Moon BH, Bae JJ, Joo MK, Choi H, Han GH, Lim H, Lee YH. Soft Coulomb gap and asymmetric scaling towards metal-insulator quantum criticality in multilayer MoS 2. Nat Commun 2018; 9:2052. [PMID: 29795384 PMCID: PMC5967350 DOI: 10.1038/s41467-018-04474-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Accepted: 04/30/2018] [Indexed: 11/09/2022] Open
Abstract
Quantum localization–delocalization of carriers are well described by either carrier–carrier interaction or disorder. When both effects come into play, however, a comprehensive understanding is not well established mainly due to complexity and sparse experimental data. Recently developed two-dimensional layered materials are ideal in describing such mesoscopic critical phenomena as they have both strong interactions and disorder. The transport in the insulating phase is well described by the soft Coulomb gap picture, which demonstrates the contribution of both interactions and disorder. Using this picture, we demonstrate the critical power law behavior of the localization length, supporting quantum criticality. We observe asymmetric critical exponents around the metal-insulator transition through temperature scaling analysis, which originates from poor screening in insulating regime and conversely strong screening in metallic regime due to free carriers. The effect of asymmetric scaling behavior is weakened in monolayer MoS2 due to a dominating disorder. The interplay between strong interactions and presence of disorder makes atomically thin transition metal dichalcogenides an ideal platform to study phase transitions and critical phenomena. Here, the authors observe asymmetric critical exponents around the metal-insulator-transition of multilayer MoS2.
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Affiliation(s)
- Byoung Hee Moon
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea. .,Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
| | - Jung Jun Bae
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
| | - Min-Kyu Joo
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
| | - Homin Choi
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea.,Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Gang Hee Han
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
| | - Hanjo Lim
- Institute for Basic Science (IBS), Daejeon, 34047, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea. .,Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
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11
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Scaling analysis of field-tuned superconductor-insulator transition in two-dimensional tantalum thin films. Sci Rep 2017; 7:42969. [PMID: 28218296 PMCID: PMC5317156 DOI: 10.1038/srep42969] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/17/2017] [Indexed: 11/08/2022] Open
Abstract
The superconductor–insulator (SI) transition in two-dimensional Ta thin films is investigated by controlling both film thickness and magnetic field. An intriguing metallic phase appears between a superconducting and an insulating phase within a range of film thickness and magnetic field. The temperature and electric field scaling analyses are performed to investigate the nature of the SI transition in the thickness-tuned metallic and superconducting samples. The critical exponents product of νz obtained from the temperature scaling analysis is found to be approximately 0.67 in the entire range of film thickness. On the other hand, an apparent discrepancy is measured in the product of ν(z + 1) by the electric filed analysis. The product values are found to be about 1.37 for the superconducting films and about 1.86 for the metallic films respectively. We find that the discrepancy is the direct consequence of electron heating that introduces additional dissipation channels in the metallic Ta films.
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12
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Zhao Y, Qiao J, Yu Z, Yu P, Xu K, Lau SP, Zhou W, Liu Z, Wang X, Ji W, Chai Y. High-Electron-Mobility and Air-Stable 2D Layered PtSe 2 FETs. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1604230. [PMID: 27886410 DOI: 10.1002/adma.201604230] [Citation(s) in RCA: 224] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 10/01/2016] [Indexed: 05/23/2023]
Abstract
The electrical and optical measurements, in combination with density functional theory calculations, show distinct layer-dependent semiconductor-to-semimetal evolution of 2D layered PtSe2 . The high room-temperature electron mobility and near-infrared photo-response, together with much better air-stability, make PtSe2 a versatile electronic 2D layered material.
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Affiliation(s)
- Yuda Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, P. R. China
| | - Jingsi Qiao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
- Department of Physics, Renmin University of China, Beijing, 100872, P. R. China
- Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing, 100872, P. R. China
| | - Zhihao Yu
- National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, and, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Peng Yu
- School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
| | - Kang Xu
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
| | - Shu Ping Lau
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, P. R. China
| | - Wu Zhou
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
| | - Xinran Wang
- National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, and, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Wei Ji
- Department of Physics, Renmin University of China, Beijing, 100872, P. R. China
- Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing, 100872, P. R. China
| | - Yang Chai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, P. R. China
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13
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Pradhan NR, McCreary A, Rhodes D, Lu Z, Feng S, Manousakis E, Smirnov D, Namburu R, Dubey M, Walker ARH, Terrones H, Terrones M, Dobrosavljevic V, Balicas L. Metal to Insulator Quantum-Phase Transition in Few-Layered ReS₂. NANO LETTERS 2015; 15:8377-8384. [PMID: 26599563 DOI: 10.1021/acs.nanolett.5b04100] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In ReS2, a layer-independent direct band gap of 1.5 eV implies a potential for its use in optoelectronic applications. ReS2 crystallizes in the 1T'-structure, which leads to anisotropic physical properties and whose concomitant electronic structure might host a nontrivial topology. Here, we report an overall evaluation of the anisotropic Raman response and the transport properties of few-layered ReS2 field-effect transistors. We find that ReS2 exfoliated on SiO2 behaves as an n-type semiconductor with an intrinsic carrier mobility surpassing μ(i) ∼ 30 cm(2)/(V s) at T = 300 K, which increases up to ∼350 cm(2)/(V s) at 2 K. Semiconducting behavior is observed at low electron densities n, but at high values of n the resistivity decreases by a factor of >7 upon cooling to 2 K and displays a metallic T(2)-dependence. This suggests that the band structure of 1T'-ReS2 is quite susceptible to an electric field applied perpendicularly to the layers. The electric-field induced metallic state observed in transition metal dichalcogenides was recently claimed to result from a percolation type of transition. Instead, through a scaling analysis of the conductivity as a function of T and n, we find that the metallic state of ReS2 results from a second-order metal-to-insulator transition driven by electronic correlations. This gate-induced metallic state offers an alternative to phase engineering for producing ohmic contacts and metallic interconnects in devices based on transition metal dichalcogenides.
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Affiliation(s)
- Nihar R Pradhan
- National High Magnetic Field Lab, Florida State University , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Amber McCreary
- Department of Physics and Center for 2-Dimensional and Layered Materials, Pennsylvania State University , University Park, State College, Pennsylvania 16802, United States
- Computational & Information Sciences Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States
- Sensor & Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States
| | - Daniel Rhodes
- National High Magnetic Field Lab, Florida State University , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
- Department of Physics, Florida State University , Tallahassee, Florida 32306, United States
| | - Zhengguang Lu
- National High Magnetic Field Lab, Florida State University , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
- Department of Physics, Florida State University , Tallahassee, Florida 32306, United States
| | - Simin Feng
- Department of Physics and Center for 2-Dimensional and Layered Materials, Pennsylvania State University , University Park, State College, Pennsylvania 16802, United States
| | - Efstratios Manousakis
- National High Magnetic Field Lab, Florida State University , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
- Department of Physics, Florida State University , Tallahassee, Florida 32306, United States
| | - Dmitry Smirnov
- National High Magnetic Field Lab, Florida State University , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Raju Namburu
- Computational & Information Sciences Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States
| | - Madan Dubey
- Sensor & Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States
| | - Angela R Hight Walker
- Engineering Physics Division, Physics Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Humberto Terrones
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States
| | - Mauricio Terrones
- Department of Physics and Center for 2-Dimensional and Layered Materials, Pennsylvania State University , University Park, State College, Pennsylvania 16802, United States
- Department of Chemistry and Department of Materials Science and Engineering, The Pennsylvania State University , University Park, State College, Pennsylvania 16802, United States
- Carbon Institute of Science and Technology, Shinshu University , Wakasato 4-17-1, Nagano-city 380-8553, Japan
| | - Vladimir Dobrosavljevic
- National High Magnetic Field Lab, Florida State University , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
- Department of Physics, Florida State University , Tallahassee, Florida 32306, United States
| | - Luis Balicas
- National High Magnetic Field Lab, Florida State University , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
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14
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Xiang S, Fuji K, Sato S, Xiao S, Bird JP, Aoki N, Ochiai Y. Metal-insulator transition in the quasi-one-dimensional transport of fractional quantum Hall states. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:202201. [PMID: 25920938 DOI: 10.1088/0953-8984/27/20/202201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate edge state transmission in quantum point contacts (QPCs) in the fractional quantum-Hall regime, finding behavior reminiscent of a metal-insulator transition. The transition is suggested by an unusual behavior of the differential conductance in the fractional-quantum-Hall regime, and by the presence of a fixed point and universal scaling in the temperature dependence of the linear conductance. Noting that the 0.7 feature evolves continuously into a last fractional plateau at high magnetic fields, we suggest that this still unresolved feature may itself be viewed as a manifestation of a local, microscopic, metal-insulator transition.
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Affiliation(s)
- S Xiang
- Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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15
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Lin PV, Popović D. Critical Behavior of a Strongly Disordered 2D Electron System: The Cases of Long-Range and Screened Coulomb Interactions. PHYSICAL REVIEW LETTERS 2015; 114:166401. [PMID: 25955059 DOI: 10.1103/physrevlett.114.166401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Indexed: 06/04/2023]
Abstract
A study of the temperature (T) and density (ns) dependence of conductivity σ(ns,T) of a highly disordered, two-dimensional (2D) electron system in Si demonstrates scaling behavior consistent with the existence of a metal-insulator transition (MIT). The same critical exponents are found when the Coulomb interaction is screened by the metallic gate and when it is unscreened or long range. The results strongly suggest the existence of a disorder-dominated 2D MIT, which is not directly affected by the range of the Coulomb interactions.
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Affiliation(s)
- Ping V Lin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Dragana Popović
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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16
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Limtragool K, Phillips PW. Divergent thermopower without a quantum phase transition. PHYSICAL REVIEW LETTERS 2014; 113:086405. [PMID: 25192114 DOI: 10.1103/physrevlett.113.086405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Indexed: 06/03/2023]
Abstract
A general principle of modern statistical physics is that divergences of either thermodynamic or transport properties are only possible if the correlation length diverges. We show by explicit calculation that the thermopower in the quantum XY model d = 1 + 1 and the Kitaev model in d = 2 + 1 can (i) diverge even when the correlation length is finite and (ii) remain finite even when the correlation length diverges, thereby providing a counterexample to the standard paradigm. Two conditions are necessary: (i) the sign of the charge carriers and that of the group velocity must be uncorrelated and (ii) the current operator defined formally as the derivative of the Hamiltonian with respect to the gauge field does not describe a set of excitations that have a particle interpretation, as in strongly correlated electron matter. Recent experimental and theoretical findings on the divergent thermopower of a 2D electron gas are discussed in this context.
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Affiliation(s)
- Kridsanaphong Limtragool
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801, USA
| | - Philip W Phillips
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801, USA
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17
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Gasparian V, Cahay M, Jódar E. Localization length in a quasi-one-dimensional disordered system in the presence of an electric field. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:045301. [PMID: 21406884 DOI: 10.1088/0953-8984/23/4/045301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A two-dimensional δ-potential Kronig-Penney model for quasi-one-dimensional (Q1D) disordered systems is used to study analytically the influence of a constant electric field on the inverse localization length (LL). Based on the Green's function formalism we have calculated LL as a function of the incoming energy E, electric field F, length L of the Q1D sample, number of modes M in the transverse direction and the amount of disorder w. We show that, for large L in Q1D systems, states are weakly localized, i.e. we deal with power-law localization. With increasing electric field in Q1D mesoscopic systems a transition from exponential to a power-law behavior takes place, as in 1D systems. We note that the graphs showing the inverse LL change significantly with increasing F (for fixed M) rather than with increasing M (for fixed F). We also show that the graphs representing the ratio of the corresponding localization length without and with electric field collapse for all modes M into a universal curve in the Q1D strip model.
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Affiliation(s)
- Vladimir Gasparian
- Department of Physics, California State University, Bakersfield, CA 93311, USA.
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18
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Chakravarty S, Kivelson S, Nayak C, Voelker K. Wigner glass, spin liquids and the metal-insulator transition. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/13642819908214845] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Sudip Chakravarty
- a Department of Physics and Astronomy , University of California Los Angeles , Los Angeles , California , 90095-1547 , USA
| | - Steven Kivelson
- a Department of Physics and Astronomy , University of California Los Angeles , Los Angeles , California , 90095-1547 , USA
| | - Cheta Nayak
- a Department of Physics and Astronomy , University of California Los Angeles , Los Angeles , California , 90095-1547 , USA
| | - Klaus Voelker
- a Department of Physics and Astronomy , University of California Los Angeles , Los Angeles , California , 90095-1547 , USA
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19
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Manyala N, DiTusa JF, Aeppli G, Ramirez AP. Doping a semiconductor to create an unconventional metal. Nature 2008; 454:976-80. [DOI: 10.1038/nature07137] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Accepted: 05/23/2008] [Indexed: 11/09/2022]
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20
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Li Z, Li G, Wang NL, Luo JL. The metal-insulator-like and insulator-metal-like behaviors in antimony. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:235232. [PMID: 21694323 DOI: 10.1088/0953-8984/20/23/235232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The resistivity and Hall resistivity of semimetallic antimony were measured from 2 to 300 K in magnetic fields up to 14 T. We found that in low field, the resistivity shows metallic behavior. In a modest field, the resistivity decreases to a minimum and then increases with decreasing temperature, showing a metal-insulator-like transition. In high field, the resistivity drops at low temperatures, showing an insulator-metal-like transition. The metal-insulator-like behavior can be explained by the competition of zero field resistivity and magneto-resistance, which is reciprocal to the zero field resistivity. The insulator-metal-like behavior can be explained by the imbalance of two carrier densities which changes the magneto-resistance from being reciprocal to proportional to the zero field resistivity.
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Affiliation(s)
- Z Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People's Republic of China
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21
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22
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Disorder, electron-electron interactions and the metal-insulator transition in heavily doped Si:P. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/bfb0108351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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23
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Heidarian D, Trivedi N. Inhomogeneous metallic phase in a disordered Mott insulator in two dimensions. PHYSICAL REVIEW LETTERS 2004; 93:126401. [PMID: 15447287 DOI: 10.1103/physrevlett.93.126401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2003] [Indexed: 05/24/2023]
Abstract
We show that, with increasing randomness, the spectral gap in a 2D Mott-Hubbard insulator is destroyed first at a disorder V(c1), while antiferromagnetism persists up to a higher V(c2). Most unexpectedly, between V(c1) and V(c2) the system is metallic and is sandwiched between the Mott insulator below V(c1) and the Anderson insulator above V(c2). The metal is formed when the spectral gap gets destroyed locally in regions where the disorder potential is high enough to overcome the interelectron repulsion. This generates puddles with enhanced charge fluctuations that percolate with increasing disorder, resulting in a spatially inhomogeneous metallic phase.
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Affiliation(s)
- Dariush Heidarian
- Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005, India
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24
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Dalidovich D, Phillips P. Nonlinear transport near a quantum phase transition in two dimensions. PHYSICAL REVIEW LETTERS 2004; 93:027004. [PMID: 15323944 DOI: 10.1103/physrevlett.93.027004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2003] [Indexed: 05/24/2023]
Abstract
The problem of nonlinear transport near a quantum phase transition is solved within the Landau theory for the dissipative insulator-superconductor phase transition in two dimensions. Using the nonequilibrium Schwinger round-trip Green function formalism, we obtain the scaling function for the nonlinear conductivity in the quantum-disordered regime. We find that the conductivity scales as E2 at low fields but crosses over at large fields to a universal constant on the order of e(2)/h. The crossover between these two regimes obtains when the length scale for the quantum fluctuations becomes comparable to that of the electric field within logarithmic accuracy.
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Affiliation(s)
- Denis Dalidovich
- National High Field Magnetic Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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25
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Denteneer PJH, Scalettar RT. Interacting electrons in a two-dimensional disordered environment: effect of a zeeman magnetic field. PHYSICAL REVIEW LETTERS 2003; 90:246401. [PMID: 12857206 DOI: 10.1103/physrevlett.90.246401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2003] [Indexed: 05/24/2023]
Abstract
The effect of a Zeeman magnetic field coupled to the spin of the electrons on the conducting properties of the disordered Hubbard model is studied. Using the determinant quantum Monte Carlo method, the temperature- and magnetic-field-dependent conductivity is calculated, as well as the degree of spin polarization. We find that the Zeeman magnetic field suppresses the metallic behavior present for certain values of interaction and disorder strength and is able to induce a metal-insulator transition at a critical field strength. It is argued that the qualitative features of magnetoconductance in this microscopic model containing both repulsive interactions and disorder are in agreement with experimental findings in two-dimensional electron and hole gases in semiconductor structures.
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Affiliation(s)
- P J H Denteneer
- Lorentz Institute, Leiden University, PO Box 9506, 2300 RA Leiden, The Netherlands
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26
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27
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Shashkin AA, Kravchenko SV, Klapwijk TM. Metal-insulator transition in a 2D electron gas: equivalence of two approaches for determining the critical point. PHYSICAL REVIEW LETTERS 2001; 87:266402. [PMID: 11800848 DOI: 10.1103/physrevlett.87.266402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2001] [Indexed: 05/23/2023]
Abstract
The critical electron density for the metal-insulator transition in a two-dimensional electron gas can be determined by two distinct methods: (i) a sign change of the temperature derivative of the resistance, and (ii) vanishing activation energy and vanishing nonlinearity of current-voltage characteristics as extrapolated from the insulating side. We find that, in zero magnetic field (but not in the presence of a parallel magnetic field), both methods give equivalent results, adding support to the existence of a true zero-field metal-insulator transition.
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Affiliation(s)
- A A Shashkin
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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28
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Vitkalov SA, Zheng H, Mertes KM, Sarachik MP, Klapwijk TM. Scaling of the magnetoconductivity of silicon MOSFETs: evidence for a quantum phase transition in two dimensions. PHYSICAL REVIEW LETTERS 2001; 87:086401. [PMID: 11497966 DOI: 10.1103/physrevlett.87.086401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2000] [Revised: 05/08/2001] [Indexed: 05/23/2023]
Abstract
For a broad range of electron densities n and temperatures T, the in-plane magnetoconductivity of the two-dimensional system of electrons in silicon MOSFETs can be scaled onto a universal curve with a single parameter H(sigma)(n,T), where H(sigma) obeys the empirical relation H(sigma) = A(n) [Delta(n)(2)+T2](1/2). The characteristic energy k(B)Delta associated with the magnetic field dependence of the conductivity decreases with decreasing density, and extrapolates to 0 at a critical density n(0), signaling the approach to a zero-temperature quantum phase transition. We show that H(sigma) = AT for densities near n(0).
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Affiliation(s)
- S A Vitkalov
- Physics Department, City College of the City University of New York, New York, New York 10031, USA
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29
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Tutuc E, De Poortere EP, Papadakis SJ, Shayegan M. In-plane magnetic field-induced spin polarization and transition to insulating behavior in two-dimensional hole systems. PHYSICAL REVIEW LETTERS 2001; 86:2858-2861. [PMID: 11290057 DOI: 10.1103/physrevlett.86.2858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2000] [Indexed: 05/23/2023]
Abstract
Using a novel technique, we make quantitative measurements of the spin polarization of dilute [ (3.4-6.8)x10(10) cm(-2)] GaAs (311)A two-dimensional holes as a function of an in-plane magnetic field. As the field is increased the system gradually becomes spin polarized, with the degree of spin polarization depending on the orientation of the field relative to the crystal axes. Moreover, the behavior of the system turns from metallic to insulating before it is fully spin polarized. The minority-spin population at the transition is approximately 8x10(9) cm(-2), close to the density below which the system makes a transition to an insulating state in the absence of a magnetic field.
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Affiliation(s)
- E Tutuc
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
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30
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Feng XG, Popović D, Washburn S, Dobrosavljević V. Novel metallic behavior in two dimensions. PHYSICAL REVIEW LETTERS 2001; 86:2625-2628. [PMID: 11289996 DOI: 10.1103/physrevlett.86.2625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/1999] [Indexed: 05/23/2023]
Abstract
Experiments on a sufficiently disordered two-dimensional (2D) electron system in silicon reveal a new and unexpected kind of metallic behavior, where the conductivity decreases as sigma(n(s),T) = sigma(n(s),T = 0)+A(n(s))T(2) (where n(s) is carrier density) to a nonzero value as temperature T-->0. In 2D, the existence of a metal with dsigma/dT>0 is very surprising. In addition, a novel type of a metal-insulator transition obtains, which is unlike any known quantum phase transition in 2D.
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Affiliation(s)
- X G Feng
- National High Magnetic Field Laboratory, Florida State University, Tallahassee 32310, USA
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31
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Cândido L, Phillips P, Ceperley DM. Single and paired point defects in a 2D Wigner crystal. PHYSICAL REVIEW LETTERS 2001; 86:492-495. [PMID: 11177863 DOI: 10.1103/physrevlett.86.492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2000] [Indexed: 05/23/2023]
Abstract
Using the path-integral Monte Carlo method, we calculate the energy to form single and pair vacancies and interstitials in a two-dimensional Wigner crystal of electrons. We confirm that the lowest energy point defects of a 2D electron Wigner crystal are interstitials, with a creation energy roughly 2/3 that of a vacancy. The formation energy of the defects goes to zero at melting, suggesting that point defects may be the melting mechanism and that the melting could be a continuous transition. In addition, we find that the interaction between defects is strongly attractive, so that most defects will exist as bound pairs.
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Affiliation(s)
- L Cândido
- Loomis Laboratory of Physics and NCSA, University of Illinois at Urbana-Champaign, 1100 West Green Street, Urbana, Illinois 61801-3080, USA
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32
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Safonov SS, Roshko SH, Savchenko AK, Pogosov AG, Kvon ZD. "Metallic" and "insulating" behavior of the two-dimensional electron gas on a vicinal surface of Si MOSFET'S. PHYSICAL REVIEW LETTERS 2001; 86:272-275. [PMID: 11177809 DOI: 10.1103/physrevlett.86.272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2000] [Indexed: 05/23/2023]
Abstract
The resistance R of the 2DEG on the vicinal Si surface shows unusual behavior which is very different from that in Si (100) MOSFET's studied earlier. The low-temperature crossover from dR/dT<0 ("insulator") to dR/dT>0 ("metal") occurs at a low resistance of R(c)square approximately 0.04xh/e2. This crossover, which we attribute to the existence of a narrow impurity band at the interface, is accompanied by a distinct hysteresis in the resistance. At higher temperatures, another change in the sign of dR/dT is seen. We describe it by temperature dependent impurity scattering of the 2DEG near the transition from the degenerate to nondegenerate state.
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Affiliation(s)
- S S Safonov
- School of Physics, University of Exeter, United Kingdom
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33
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Chamon C, Mucciolo ER. Nonperturbative saddle point for the effective action of disordered and interacting electrons in 2D. PHYSICAL REVIEW LETTERS 2000; 85:5607-5610. [PMID: 11136058 DOI: 10.1103/physrevlett.85.5607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2000] [Indexed: 05/23/2023]
Abstract
We find a nonperturbative saddle-point solution for the nonlinear sigma model proposed by Finkelstein for interacting and disordered electronic systems. Spin rotation symmetry, present in the original saddle-point solution, is spontaneously broken at one loop, as in the Coleman-Weinberg mechanism. The new solution is singular in both the disorder and triplet interaction strengths, and it also explicitly demonstrates that a nontrivial ferromagnetic state appears in a theory where the disorder average is carried out from the outset.
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Affiliation(s)
- C Chamon
- Department of Physics, Boston University, Boston, Massachusetts, USA
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34
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Vidal J, Doucot B, Mosseri R, Butaud P. Interaction induced delocalization for two particles in a periodic potential. PHYSICAL REVIEW LETTERS 2000; 85:3906-3909. [PMID: 11041957 DOI: 10.1103/physrevlett.85.3906] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2000] [Indexed: 05/23/2023]
Abstract
We consider two interacting particles evolving in a one-dimensional periodic structure embedded in a magnetic field. We show that the strong localization induced by the magnetic field for particular values of the flux per unit cell is destroyed as soon as the particles interact. We study the spectral and dynamical aspects of this transition.
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Affiliation(s)
- J Vidal
- Laboratoire de Physique des Solides, CNRS UMR 8502, Universite Paris Sud, Batiment 510, 91405 Orsay, France
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35
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Schakel AM. Self-duality in superconductor-insulator quantum phase transitions. PHYSICAL REVIEW LETTERS 2000; 85:3934-3937. [PMID: 11041964 DOI: 10.1103/physrevlett.85.3934] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2000] [Indexed: 05/23/2023]
Abstract
It is argued that close to a Coulomb interacting quantum critical point the interaction between two vortices in a disordered superconducting thin film separated by a distance r changes from logarithmic in the mean-field region to 1/r in the region dominated by quantum critical fluctuations. This gives support to the charge-vortex duality picture of the observed reflection symmetry in the current-voltage characteristics on both sides of the transition.
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Affiliation(s)
- AM Schakel
- Low Temperature Laboratory, Helsinki University of Technology, P.O. Box 2200, FIN-02015 HUT, Finland and and Institut fur Theoretische Physik, Freie Universitat Berlin, Arnimallee 14, 14195 Berlin, Germany
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36
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Gold A, Dolgopolov VT. Comment on "Charged impurity-scattering-limited low-temperature resistivity of low-density silicon inversion layers". PHYSICAL REVIEW LETTERS 2000; 85:3541. [PMID: 11030942 DOI: 10.1103/physrevlett.85.3541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/1999] [Indexed: 05/23/2023]
Affiliation(s)
- A Gold
- Centre d'Elaboration de Materiaux et d'Etudes Structurales 29 Rue Jeanne Marvig, 31055 Toulouse, France
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37
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Vitkalov SA, Zheng H, Mertes KM, Sarachik MP, Klapwijk TM. Small-angle shubnikov-de haas measurements in a 2D electron system: the effect of a strong In-plane magnetic field. PHYSICAL REVIEW LETTERS 2000; 85:2164-2167. [PMID: 10970488 DOI: 10.1103/physrevlett.85.2164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2000] [Indexed: 05/23/2023]
Abstract
Measurements in magnetic fields applied at small angles relative to the electron plane in silicon MOSFETs indicate a factor of 2 increase of the frequency of Shubnikov-de Haas oscillations at H>H(sat). This signals the onset of full spin polarization above H(sat), the parallel field above which the resistivity saturates to a constant value. For H<H(sat), the phase of the second harmonic of the oscillations relative to the first is consistent with scattering events that depend on the overlap instead of the sum of the spin-up and spin-down densities of states. This unusual behavior may reflect the importance of many-body interactions.
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Affiliation(s)
- SA Vitkalov
- Physics Department, City College of the City University of New York, New York, New York 10031, USA
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38
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Kuznetsov VV, Mendez EE, Zuo X, Snider GL, Croke ET. Partially suppressed shot noise in hopping conduction: observation in SiGe quantum wells. PHYSICAL REVIEW LETTERS 2000; 85:397-400. [PMID: 10991292 DOI: 10.1103/physrevlett.85.397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2000] [Indexed: 05/23/2023]
Abstract
We have observed shot noise in the hopping conduction of two-dimensional carriers confined in a p-type SiGe quantum well at a temperature of 4 K. Moreover, shot noise is suppressed relative to its "classical" value 2eI by an amount that depends on the length of the sample and the carrier density. We have found a suppression factor to the classical value of about one-half for a 2 &mgr;m long sample, and of one-fifth for a 5 &mgr;m sample. In each case, the factor decreased slightly as the density increased toward the insulator-metal transition. We explain these results in terms of the characteristic length ( approximately 1 &mgr;m in our case) of the inherent inhomogeneity of hopping transport, obtained from percolation theory.
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Affiliation(s)
- VV Kuznetsov
- Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York 11794-3800, USA
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39
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Papadakis SJ, Shayegan M, Winkler R. Anisotropic magnetoresistance of two-dimensional holes in GaAs. PHYSICAL REVIEW LETTERS 2000; 84:5592-5595. [PMID: 10991002 DOI: 10.1103/physrevlett.84.5592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/1999] [Indexed: 05/23/2023]
Abstract
Experiments on high-quality GaAs (311)A two-dimensional holes at low temperatures reveal a remarkable dependence of the magnetoresistance, measured with an in-plane magnetic field ( B), on the direction of B relative to both the crystal axes and the current direction. The magnetoresistance features, and in particular the value of B above which the resistivity exhibits an insulating behavior, depend on the orientation of B. To explain the data, the anisotropic band structure of the holes and a repopulation of the spin subbands in the presence of B, as well as the coupling of the orbital motion to B, need to be taken into account.
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Affiliation(s)
- SJ Papadakis
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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40
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Dultz SC, Jiang HW. Thermodynamic signature of a two-dimensional metal-insulator transition. PHYSICAL REVIEW LETTERS 2000; 84:4689-4692. [PMID: 10990772 DOI: 10.1103/physrevlett.84.4689] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/1999] [Indexed: 05/23/2023]
Abstract
We present a study of the compressibility kappa of a two-dimensional hole system which exhibits a metal-insulator phase transition at zero magnetic field. It has been observed that dkappa/dp changes sign at the critical density for the metal-insulator transition. Measurements also indicate that the insulating phase is incompressible for all values of B. Finally, we show how the phase transition evolves as the magnetic field is varied and construct a phase diagram in the density-magnetic field plane for this system.
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Affiliation(s)
- SC Dultz
- Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, California 90095, USA
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41
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Yoon J, Li CC, Shahar D, Tsui DC, Shayegan M. Parallel magnetic field induced transition in transport in the dilute two-dimensional hole system in GaAs. PHYSICAL REVIEW LETTERS 2000; 84:4421-4424. [PMID: 10990701 DOI: 10.1103/physrevlett.84.4421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/1999] [Indexed: 05/23/2023]
Abstract
A magnetic field applied parallel to the two-dimensional hole system in the GaAs/AlGaAs heterostructure, which is metallic in the absence of an external magnetic field, can drive the system into insulating at a finite field through a well-defined transition. The value of resistivity at the transition is found to depend strongly on density.
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Affiliation(s)
- J Yoon
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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42
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Ilani S, Yacoby A, Mahalu D, Shtrikman H. Unexpected behavior of the local compressibility near the B = 0 metal-insulator transition. PHYSICAL REVIEW LETTERS 2000; 84:3133-3136. [PMID: 11019030 DOI: 10.1103/physrevlett.84.3133] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/1999] [Indexed: 05/23/2023]
Abstract
We have measured the local electronic compressibility of a two-dimensional hole gas as it crosses the B = 0 metal-insulator transition. In the metallic phase, the compressibility follows the mean-field Hartree-Fock (HF) theory and is found to be spatially homogeneous. In the insulating phase it deviates by more than an order of magnitude from the HF predictions and is spatially inhomogeneous. The crossover density between the two types of behavior agrees quantitatively with the transport critical density, suggesting that the system undergoes a thermodynamic change at the transition.
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Affiliation(s)
- S Ilani
- Braun Center for Submicron Research, Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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43
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Husmann A, Brooke J, Rosenbaum TF, Yao X, Honig JM. Nonlinear electric field effects at a continuous mott-hubbard transition. PHYSICAL REVIEW LETTERS 2000; 84:2465-2468. [PMID: 11018911 DOI: 10.1103/physrevlett.84.2465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/1999] [Indexed: 05/23/2023]
Abstract
We characterize the non-Ohmic portion of the conductivity at temperatures T<1 K in the highly correlated transition metal chalcogenide Ni(S,Se)(2). Pressure tuning of the T = 0 metal-insulator transition reveals the influence of the quantum critical point and permits a direct determination of the dynamical critical exponent z = 2.7(+0.3)(-0.4). Within the framework of finite temperature scaling, we find that the spatial correlation length exponent nu and the conductivity exponent &mgr; differ.
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Affiliation(s)
- A Husmann
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, England
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44
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Phillips P, Sachdev S, Kravchenko S, Yazdani A. Quantum conductors in a plane. Proc Natl Acad Sci U S A 1999; 96:9983-4. [PMID: 10468543 PMCID: PMC33722 DOI: 10.1073/pnas.96.18.9983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- P Phillips
- Loomis Laboratory of Physics, University of Illinois at Urbana-Champaign, 1100 West Green Street, Urbana, IL 61801-3080, USA
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45
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Zhitenev NB, Brodsky M, Ashoori RC, Pfeiffer LN, West KW. Localization-delocalization transition in quantum dots. Science 1999; 285:715-8. [PMID: 10426989 DOI: 10.1126/science.285.5428.715] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Single-electron capacitance spectroscopy precisely measures the energies required to add individual electrons to a quantum dot. The spatial extent of electronic wave functions is probed by investigating the dependence of these energies on changes in the dot confining potential. For low electron densities, electrons occupy distinct spatial sites localized within the dot. At higher densities, the electrons become delocalized, and all wave functions are spread over the full dot area. Near the delocalization transition, the last remaining localized states exist at the perimeter of the dot. Unexpectedly, these electrons appear to bind with electrons in the dot center.
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Affiliation(s)
- NB Zhitenev
- Department of Physics and Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA
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46
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Sarachik MP, Kravchenko SV. Novel phenomena in dilute electron systems in two dimensions. Proc Natl Acad Sci U S A 1999; 96:5900-2. [PMID: 10339515 PMCID: PMC34203 DOI: 10.1073/pnas.96.11.5900] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
For the past two decades, all two-dimensional systems of electrons were believed to be insulating in the limit of zero temperature. Recent experiments provide evidence for an unexpected transition to a conducting phase at very low electron densities. The nature of this phase is not understood and is currently the focus of intense theoretical and experimental attention.
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Affiliation(s)
- M P Sarachik
- Physics Department, City College of the City University of New York, New York, NY 10031, USA
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47
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Papadakis SJ, Manoharan HC, Shayegan M, Winkler R. The effect of spin splitting on the metallic behavior of a two-dimensional system. Science 1999; 283:2056-8. [PMID: 10092222 DOI: 10.1126/science.283.5410.2056] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Experiments on a constant-density two-dimensional hole system in a gallium arsenide quantum well revealed that the metallic behavior observed in the zero-magnetic-field temperature dependence of the resistivity depends on the symmetry of the confinement potential and the resulting spin splitting of the valence band.
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Affiliation(s)
- SJ Papadakis
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA. Institut fur Technische Physik III, Universitat Erlangen-Nurnberg, Staudtstrasse 7, D-91058 Erlangen, Germany
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48
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Phillips P, Wan Y, Martin I, Knysh S, Dalidovich D. Superconductivity in a two-dimensional electron gas. Nature 1998. [DOI: 10.1038/26179] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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