1
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Johansson A. Theory of spin and orbital Edelstein effects. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:423002. [PMID: 38955339 DOI: 10.1088/1361-648x/ad5e2b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Accepted: 07/01/2024] [Indexed: 07/04/2024]
Abstract
In systems with broken spatial inversion symmetry, such as surfaces, interfaces, or bulk systems lacking an inversion center, the application of a charge current can generate finite spin and orbital densities associated with a nonequilibrium magnetization, which is known as spin and orbital Edelstein effect (SEE and OEE), respectively. Early reports on this current-induced magnetization focus on two-dimensional Rashba systems, in which an in-plane nonequilibrium spin density is generated perpendicular to the applied charge current. However, until today, a large variety of materials have been theoretically predicted and experimentally demonstrated to exhibit a sizeable Edelstein effect, which comprises contributions from the spin as well as the orbital degrees of freedom, and whose associated magnetization may be out of plane, nonorthogonal, and even parallel to the applied charge current, depending on the system's particular symmetries. In this review, we give an overview on the most commonly used theoretical approaches for the discussion and prediction of the SEE and OEE. Further, we introduce a selection of the most intensely discussed materials exhibiting a finite Edelstein effect, and give a brief summary of common experimental techniques.
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Affiliation(s)
- Annika Johansson
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
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2
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Qi R, Joe AY, Zhang Z, Zeng Y, Zheng T, Feng Q, Xie J, Regan E, Lu Z, Taniguchi T, Watanabe K, Tongay S, Crommie MF, MacDonald AH, Wang F. Thermodynamic behavior of correlated electron-hole fluids in van der Waals heterostructures. Nat Commun 2023; 14:8264. [PMID: 38092731 PMCID: PMC10719388 DOI: 10.1038/s41467-023-43799-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023] Open
Abstract
Coupled two-dimensional electron-hole bilayers provide a unique platform to study strongly correlated Bose-Fermi mixtures in condensed matter. Electrons and holes in spatially separated layers can bind to form interlayer excitons, composite Bosons expected to support high-temperature exciton condensates. The interlayer excitons can also interact strongly with excess charge carriers when electron and hole densities are unequal. Here, we use optical spectroscopy to quantitatively probe the local thermodynamic properties of strongly correlated electron-hole fluids in MoSe2/hBN/WSe2 heterostructures. We observe a discontinuity in the electron and hole chemical potentials at matched electron and hole densities, a definitive signature of an excitonic insulator ground state. The excitonic insulator is stable up to a Mott density of ~0.8 × 1012 cm-2 and has a thermal ionization temperature of ~70 K. The density dependence of the electron, hole, and exciton chemical potentials reveals strong correlation effects across the phase diagram. Compared with a non-interacting uniform charge distribution, the correlation effects lead to significant attractive exciton-exciton and exciton-charge interactions in the electron-hole fluid. Our work highlights the unique quantum behavior that can emerge in strongly correlated electron-hole systems.
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Affiliation(s)
- Ruishi Qi
- Department of Physics, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Andrew Y Joe
- Department of Physics, University of California, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Zuocheng Zhang
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Yongxin Zeng
- Department of Physics, University of Texas at Austin, Austin, TX, 78712, USA
| | - Tiancheng Zheng
- Department of Physics, University of California, Berkeley, CA, 94720, USA
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Qixin Feng
- Department of Physics, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jingxu Xie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Emma Regan
- Department of Physics, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Zheyu Lu
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, TX, 78712, USA
| | - Feng Wang
- Department of Physics, University of California, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Kavli Energy NanoSciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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3
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Mullan C, Slizovskiy S, Yin J, Wang Z, Yang Q, Xu S, Yang Y, Piot BA, Hu S, Taniguchi T, Watanabe K, Novoselov KS, Geim AK, Fal'ko VI, Mishchenko A. Mixing of moiré-surface and bulk states in graphite. Nature 2023; 620:756-761. [PMID: 37468634 PMCID: PMC10447246 DOI: 10.1038/s41586-023-06264-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 05/25/2023] [Indexed: 07/21/2023]
Abstract
Van der Waals assembly enables the design of electronic states in two-dimensional (2D) materials, often by superimposing a long-wavelength periodic potential on a crystal lattice using moiré superlattices1-9. This twistronics approach has resulted in numerous previously undescribed physics, including strong correlations and superconductivity in twisted bilayer graphene10-12, resonant excitons, charge ordering and Wigner crystallization in transition-metal chalcogenide moiré structures13-18 and Hofstadter's butterfly spectra and Brown-Zak quantum oscillations in graphene superlattices19-22. Moreover, twistronics has been used to modify near-surface states at the interface between van der Waals crystals23,24. Here we show that electronic states in three-dimensional (3D) crystals such as graphite can be tuned by a superlattice potential occurring at the interface with another crystal-namely, crystallographically aligned hexagonal boron nitride. This alignment results in several Lifshitz transitions and Brown-Zak oscillations arising from near-surface states, whereas, in high magnetic fields, fractal states of Hofstadter's butterfly draw deep into the bulk of graphite. Our work shows a way in which 3D spectra can be controlled using the approach of 2D twistronics.
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Affiliation(s)
- Ciaran Mullan
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
| | - Sergey Slizovskiy
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - Jun Yin
- Department of Physics and Astronomy, University of Manchester, Manchester, UK.
- State Key Laboratory of Mechanics and Control for Aerospace Structures, Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, China.
| | - Ziwei Wang
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
| | - Qian Yang
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - Shuigang Xu
- National Graphene Institute, University of Manchester, Manchester, UK
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, China
| | - Yaping Yang
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - Benjamin A Piot
- Laboratoire National des Champs Magnétiques Intenses (LNCMI), CNRS Université Grenoble Alpes, Université Toulouse 3, INSA Toulouse, EMFL, Grenoble, France
| | - Sheng Hu
- National Graphene Institute, University of Manchester, Manchester, UK
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | | | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | - Kostya S Novoselov
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
| | - A K Geim
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - Vladimir I Fal'ko
- Department of Physics and Astronomy, University of Manchester, Manchester, UK.
- National Graphene Institute, University of Manchester, Manchester, UK.
- Henry Royce Institute for Advanced Materials, Manchester, UK.
| | - Artem Mishchenko
- Department of Physics and Astronomy, University of Manchester, Manchester, UK.
- National Graphene Institute, University of Manchester, Manchester, UK.
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4
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D'Antuono M, Chen Y, Caruso R, Jouault B, Salluzzo M, Stornaiuolo D. Tuning of the magnetotransport properties of a spin-polarized 2D electron system using visible light. Sci Rep 2023; 13:10050. [PMID: 37344495 DOI: 10.1038/s41598-023-36957-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 06/13/2023] [Indexed: 06/23/2023] Open
Abstract
We report on the effects of visible light on the low temperature electronic properties of the spin-polarized two dimensional electron system (2DES) formed at the interfaces between LaAlO[Formula: see text], EuTiO[Formula: see text] and (001) SrTiO[Formula: see text]. A strong, persistent modulation of both longitudinal and transverse conductivity was obtained using light emitting diodes (LEDs) with emissions at different wavelengths in the visible spectrum range. In particular, Hall effect data show that visible light induces a non-volatile electron filling of bands with mainly 3d[Formula: see text] character, and at the same time an enhancement of the anomalous Hall effect associated to the magnetic properties of the system. Accordingly, a suppression of the weak-anti localization corrections to the magneto-conductance is found, which correlates with an enhancement of the spin-polarization and of the ferromagnetic character of 2DES. The results establish the LED-induced photo-doping as a viable route for the control of the ground state properties of artificial spin-polarized oxide 2DES.
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Affiliation(s)
- Maria D'Antuono
- Department of Physics, University of Naples Federico II, via Cinthia, 80126, Naples, Italy
- CNR-SPIN, via Cinthia, 80126, Naples, Italy
| | - Yu Chen
- CNR-SPIN, via Cinthia, 80126, Naples, Italy
| | - Roberta Caruso
- Department of Physics, University of Naples Federico II, via Cinthia, 80126, Naples, Italy
- CNR-SPIN, via Cinthia, 80126, Naples, Italy
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Bldg. 480, P.O. Box 5000, Upton, NY, 11973-5000, USA
| | - Benoit Jouault
- Laboratoire Charles Coulomb, UMR 5221, CNRS, Université de Montpellier, 34095, Montpellier, France
| | | | - Daniela Stornaiuolo
- Department of Physics, University of Naples Federico II, via Cinthia, 80126, Naples, Italy.
- CNR-SPIN, via Cinthia, 80126, Naples, Italy.
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5
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Zhao L, Lin W, Chung YJ, Gupta A, Baldwin KW, Pfeiffer LN, Liu Y. Dynamic Response of Wigner Crystals. PHYSICAL REVIEW LETTERS 2023; 130:246401. [PMID: 37390428 DOI: 10.1103/physrevlett.130.246401] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/26/2023] [Indexed: 07/02/2023]
Abstract
The Wigner crystal, an ordered array of electrons, is one of the very first proposed many-body phases stabilized by the electron-electron interaction. We examine this quantum phase with simultaneous capacitance and conductance measurements, and observe a large capacitive response while the conductance vanishes. We study one sample with four devices whose length scale is comparable with the crystal's correlation length, and deduce the crystal's elastic modulus, permittivity, pinning strength, etc. Such a systematic quantitative investigation of all properties on a single sample has a great promise to advance the study of Wigner crystals.
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Affiliation(s)
- Lili Zhao
- International Center for Quantum Materials, Peking University, Haidian, Beijing 100871, China
| | - Wenlu Lin
- International Center for Quantum Materials, Peking University, Haidian, Beijing 100871, China
| | - Yoon Jang Chung
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Adbhut Gupta
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Kirk W Baldwin
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Loren N Pfeiffer
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Yang Liu
- International Center for Quantum Materials, Peking University, Haidian, Beijing 100871, China
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6
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Raju P, Zhu H, Yang Y, Zhang K, Ioannou D, Li Q. Steep-slope transistors enabled with 2D quantum coupling stacks. NANOTECHNOLOGY 2022; 34:055001. [PMID: 36317282 DOI: 10.1088/1361-6528/ac9e5e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 10/28/2022] [Indexed: 06/16/2023]
Abstract
As down scaling of transistors continues, there is a growing interest in developing steep-slope transistors with reduced subthreshold slope (SS) below the Boltzmann limit. In this work, we successfully fabricated steep-slope MoS2transistors by incorporating a graphene layer, inserted in the gate stack. For our comprehensive study, we have applied density functional theory to simulate and calculate the change of SS effected by different 2D quantum materials, including graphene, germanene and 2D topological insulators, inserted within the gate dielectric. This theoretical study showed that graphene/MoS2devices had steep SS (27.2 mV/decade), validating our experimental approach (49.2 mV/decade). Furthermore, the simulations demonstrated very steep SS (8.6 mV/decade) in WTe2/MoS2devices. We conclude that appropriate combination of various 2D quantum materials for the gate-channel stacks, leads to steep SS and is an effective method to extend the scaling of transistors with exceptional performance.
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Affiliation(s)
- Parameswari Raju
- Department of Electrical and Computer Engineering, Fairfax, George Mason University, Fairfax, VA 22030, United States of America
- Quantum Science & Engineering Center, George Mason University, Fairfax, VA 22030, United States of America
| | - Hao Zhu
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Yafen Yang
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Kai Zhang
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Dimitris Ioannou
- Department of Electrical and Computer Engineering, Fairfax, George Mason University, Fairfax, VA 22030, United States of America
| | - Qiliang Li
- Department of Electrical and Computer Engineering, Fairfax, George Mason University, Fairfax, VA 22030, United States of America
- Quantum Science & Engineering Center, George Mason University, Fairfax, VA 22030, United States of America
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7
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Ai W, Chen J, Dong X, Gao Z, He Y, Liu Z, Fu H, Luo F, Wu J. High Mobility and Quantum Oscillations in Semiconducting Bi 2O 2Te Nanosheets Grown by Chemical Vapor Deposition. NANO LETTERS 2022; 22:7659-7666. [PMID: 36069426 DOI: 10.1021/acs.nanolett.2c02891] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Bi2O2Te has the smallest effective mass and preferable carrier mobility in the Bi2O2X (X = S, Se, Te) family. However, compared to the widely explored Bi2O2Se, the studies on Bi2O2Te are very rare, probably attributed to the lack of efficient ways to achieve the growth of ultrathin films. Herein, ultrathin Bi2O2Te crystals were successfully synthesized by a trace amount of O2-assisted chemical vapor deposition (CVD) method, enabling the observation of ultrahigh low-temperature Hall mobility of >20 000 cm2 V-1 s-1, pronounced Shubnikov-de Haas quantum oscillations, and small effective mass of ∼0.10 m0. Furthermore, few nm thick CVD-grown Bi2O2Te crystals showed high room-temperature Hall mobility (up to 500 cm2 V-1 s-1) both in nonencapsulated and top-gated device configurations and preserved the intrinsic semiconducting behavior with Ion/Ioff ∼ 103 at 300 K and >106 at 80 K. Our work uncovers the veil of semiconducting Bi2O2Te with high mobility and brings new blood into Bi2O2X family.
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Affiliation(s)
- Wei Ai
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Jiabiao Chen
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Xinyue Dong
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhansheng Gao
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Yuyu He
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhaochao Liu
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Huixia Fu
- Center of Quantum Materials and Devices and College of Physics, Chongqing University, Chongqing 401331, China
| | - Feng Luo
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Jinxiong Wu
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
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8
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Li T, Zhu J, Tang Y, Watanabe K, Taniguchi T, Elser V, Shan J, Mak KF. Charge-order-enhanced capacitance in semiconductor moiré superlattices. NATURE NANOTECHNOLOGY 2021; 16:1068-1072. [PMID: 34426680 DOI: 10.1038/s41565-021-00955-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 07/01/2021] [Indexed: 06/13/2023]
Abstract
Van der Waals moiré materials have emerged as a highly controllable platform to study electronic correlation phenomena1-17. Robust correlated insulating states have recently been discovered at both integer and fractional filling factors of semiconductor moiré systems10-17. In this study we explored the thermodynamic properties of these states by measuring the gate capacitance of MoSe2/WS2 moiré superlattices. We observed a series of incompressible states for filling factors 0-8 and anomalously large capacitance in the intervening compressible regions. The anomalously large capacitance, which was nearly 60% above the device's geometrical capacitance, was most pronounced at small filling factors, below the melting temperature of the charge-ordered states, and for small sample-gate separation. It is a manifestation of the device-geometry-dependent Coulomb interaction between electrons and phase mixing of the charge-ordered states. Based on these results, we were able to extract the thermodynamic gap of the correlated insulating states and the device's electronic entropy and specific heat capacity. Our findings establish capacitance as a powerful probe of the correlated states in semiconductor moiré systems and demonstrate control of these states via sample-gate coupling.
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Affiliation(s)
- Tingxin Li
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Jiacheng Zhu
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Yanhao Tang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | | | - Veit Elser
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - Jie Shan
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
| | - Kin Fai Mak
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
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9
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Non-universal current flow near the metal-insulator transition in an oxide interface. Nat Commun 2021; 12:3311. [PMID: 34083533 PMCID: PMC8175561 DOI: 10.1038/s41467-021-23393-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 04/21/2021] [Indexed: 11/12/2022] Open
Abstract
In systems near phase transitions, macroscopic properties often follow algebraic scaling laws, determined by the dimensionality and the underlying symmetries of the system. The emergence of such universal scaling implies that microscopic details are irrelevant. Here, we locally investigate the scaling properties of the metal-insulator transition at the LaAlO3/SrTiO3 interface. We show that, by changing the dimensionality and the symmetries of the electronic system, coupling between structural and electronic properties prevents the universal behavior near the transition. By imaging the current flow in the system, we reveal that structural domain boundaries modify the filamentary flow close to the transition point, preventing a fractal with the expected universal dimension from forming. Macroscopic properties usually follow algebraic scaling laws near phase transitions. Here, the authors investigate the scaling properties of the metal‐insulator transition at the LaAlO3/SrTiO3 interface, finding that coupling between structural and electronic properties prevents the universal behavior.
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10
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Balasubramanian K. Quantum capacitance of coupled two-dimensional electron gases. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:28LT01. [PMID: 33588395 DOI: 10.1088/1361-648x/abe64f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Quantum capacitance effect is observed in nanostructured material stacks with quantum limited density of states. In contrast to conventional structures where two-dimensional electron gases (2DEG) with reduced density of states interact with a metal plate, here we explore the quantum capacitance effect in a unique structure formed by two 2DEG in a graphene sheet and AlGaN/GaN quantum well. The total capacitance of the structure depends non-linearly on the applied potential and the linear density of states in graphene leads to enhanced electric field leakage into the substrate causing a dramatic 50% drop in the overall capacitance at low bias potentials. We show theoretical projections of the quantum capacitance effect in the proposed device stack, fabricate the structure and provide experimental verification of the calculated values at various temperatures and applied potentials. The wide swing in the total capacitance is sensitive to the chemical potential of the graphene sheet and has multiple applications in molecular sensing, electro-optics, and fundamental investigations.
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Affiliation(s)
- Krishna Balasubramanian
- Electrical Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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11
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Ye M, Hu S, Zhu Y, Zhang Y, Ke S, Xie L, Zhang Y, Hu S, Zhang D, Luo Z, Gu M, He J, Zhang P, Zhang W, Chen L. Electric Polarization Switching on an Atomically Thin Metallic Oxide. NANO LETTERS 2021; 21:144-150. [PMID: 33306405 DOI: 10.1021/acs.nanolett.0c03417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Materials with reduced dimensions have been shown to host a wide variety of exotic properties and novel quantum states that often defy textbook wisdom. Polarization switching and metallic screening are well-known examples of mutually exclusive properties that cannot coexist in bulk solids. Here we report the fabrication of (SrRuO3)1/(BaTiO3)10 superlattices that exhibits reversible polarization switching in an atomically thin metallic layer. A multipronged investigation combining structural analyses, electrical measurements, and first-principles electronic structure calculations unravels the coexistence of two-dimensional (2D) metallicity in the SrRuO3 layer accompanied by the breaking of inversion symmetry, supporting electric polarization along the out-of-plane direction. Such a 2D ferroelectric-like metal paves a novel way to engineer a quantum multistate with unusual coexisting properties, such as ferroelectrics and metals, manipulated by external fields.
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Affiliation(s)
- Mao Ye
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Songbai Hu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuanmin Zhu
- Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yubo Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Shanming Ke
- School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China
| | - Lin Xie
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuan Zhang
- School of Materials Science and Engineering, Xiangtan University, Hunan 411105, China
| | - Sixia Hu
- Core Research Facilities, Southern University of Science and Technology, Shenzhen 518055, China
| | - Dongwen Zhang
- College of Science, National University of Defense Technology, Hunan 410073, China
| | - Zhenlin Luo
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China
| | - Meng Gu
- Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jiaqing He
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Peihong Zhang
- Department of Physics, State University of New York at Buffalo, Buffalo, New York 14260, United States
| | - Wenqing Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Lang Chen
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
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Spectral weight reduction of two-dimensional electron gases at oxide surfaces across the ferroelectric transition. Sci Rep 2020; 10:16834. [PMID: 33033329 PMCID: PMC7545169 DOI: 10.1038/s41598-020-73657-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/02/2020] [Indexed: 11/11/2022] Open
Abstract
The discovery of a two-dimensional electron gas (2DEG) at the \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {LaAlO}_3/\hbox {SrTiO}_3$$\end{document}LaAlO3/SrTiO3 interface has set a new platform for all-oxide electronics which could potentially exhibit the interplay among charge, spin, orbital, superconductivity, ferromagnetism and ferroelectricity. In this work, by using angle-resolved photoemission spectroscopy and conductivity measurement, we found the reduction of 2DEGs and the changes of the conductivity nature of some ferroelectric oxides including insulating Nb-lightly-substituted \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {KTaO}_3$$\end{document}KTaO3, \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {BaTiO}_3$$\end{document}BaTiO3 (BTO) and (Ca,Zr)-doped BTO across paraelectric-ferroelectric transition. We propose that these behaviours could be due to the increase of space-charge screening potential at the 2DEG/ferroelectric regions which is a result of the realignment of ferroelectric polarisation upon light irradiation. This finding suggests an opportunity for controlling the 2DEG at a bare oxide surface (instead of interfacial system) by using both light and ferroelectricity.
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Nathabumroong S, Eknapakul T, Jaiban P, Yotburut B, Siriroj S, Saisopa T, Mo SK, Supruangnet R, Nakajima H, Yimnirun R, Maensiri S, Meevasana W. Interplay of negative electronic compressibility and capacitance enhancement in lightly-doped metal oxide Bi 0.95La 0.05FeO 3 by quantum capacitance model. Sci Rep 2020; 10:5153. [PMID: 32198381 PMCID: PMC7083945 DOI: 10.1038/s41598-020-61859-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 02/24/2020] [Indexed: 12/03/2022] Open
Abstract
Light-sensitive capacitance variation of Bi0.95La0.05FeO3 (BLFO) ceramics has been studied under violet to UV irradiation. The reversible capacitance enhancement up to 21% under 405 nm violet laser irradiation has been observed, suggesting a possible degree of freedom to dynamically control this in high dielectric materials for light-sensitive capacitance applications. By using ultraviolet photoemission spectroscopy (UPS), we show here that exposure of BLFO surfaces to UV light induces a counterintuitive shift of the O2p valence state to lower binding energy of up to 243 meV which is a direct signature of negative electronic compressibility (NEC). A decrease of BLFO electrical resistance agrees strongly with the UPS data suggesting the creation of a thin conductive layer on its insulating bulk under light irradiation. By exploiting the quantum capacitance model, we find that the negative quantum capacitance due to this NEC effect plays an important role in this capacitance enhancement
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Affiliation(s)
- S Nathabumroong
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - T Eknapakul
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - P Jaiban
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand.,Faculty of science, Energy and Environment, King Mongkut's University of Technology North Bangkok, Rayong Campus, Rayong, 21120, Thailand
| | - B Yotburut
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand.,Thailand Center of Excellence in Physics (ThEP), MHSRI, Bangkok, 10400, Thailand
| | - S Siriroj
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - T Saisopa
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - S-K Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - R Supruangnet
- Synchrotron Light Research Institute, Nakhon Ratchasima, 30000, Thailand
| | - H Nakajima
- Synchrotron Light Research Institute, Nakhon Ratchasima, 30000, Thailand
| | - R Yimnirun
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand.,School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Rayong, 21210, Thailand
| | - S Maensiri
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - W Meevasana
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand. .,Thailand Center of Excellence in Physics (ThEP), MHSRI, Bangkok, 10400, Thailand.
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14
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Panda PK, Grigoriev A, Mishra YK, Ahuja R. Progress in supercapacitors: roles of two dimensional nanotubular materials. NANOSCALE ADVANCES 2020; 2:70-108. [PMID: 36133979 PMCID: PMC9419609 DOI: 10.1039/c9na00307j] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 10/28/2019] [Indexed: 05/03/2023]
Abstract
Overcoming the global energy crisis due to vast economic expansion with the advent of human reliance on energy-consuming labor-saving devices necessitates the demand for next-generation technologies in the form of cleaner energy storage devices. The technology accelerates with the pace of developing energy storage devices to meet the requirements wherever an unanticipated burst of power is indeed needed in a very short time. Supercapacitors are predicted to be future power vehicles because they promise faster charging times and do not rely on rare elements such as lithium. At the same time, they are key nanoscale device elements for high-frequency noise filtering with the capability of storing and releasing energy by electrostatic interactions between the ions in the electrolyte and the charge accumulated at the active electrode during the charge/discharge process. There have been several developments to increase the functionality of electrodes or finding a new electrolyte for higher energy density, but this field is still open to witness the developments in reliable materials-based energy technologies. Nanoscale materials have emerged as promising candidates for the electrode choice, especially in 2D sheet and folded tubular network forms. Due to their unique hierarchical architecture, excellent electrical and mechanical properties, and high specific surface area, nanotubular networks have been widely investigated as efficient electrode materials in supercapacitors, while maintaining their inherent characteristics of high power and long cycling life. In this review, we briefly present the evolution, classification, functionality, and application of supercapacitors from the viewpoint of nanostructured materials to apprehend the mechanism and construction of advanced supercapacitors for next-generation storage devices.
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Affiliation(s)
- Pritam Kumar Panda
- Department of Physics and Astronomy, Uppsala University Box 516 SE-75120 Uppsala Sweden
| | - Anton Grigoriev
- Department of Physics and Astronomy, Uppsala University Box 516 SE-75120 Uppsala Sweden
| | - Yogendra Kumar Mishra
- Mads Clausen Institute, NanoSYD, University of Southern Denmark Alsion 2 DK-6400 Denmark
| | - Rajeev Ahuja
- Department of Materials and Engineering, Royal Institute of Technology (KTH) SE-10044 Stockholm Sweden
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15
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Lotfizadeh N, McCulley DR, Senger MJ, Fu H, Minot ED, Skinner B, Deshpande VV. Band-Gap-Dependent Electronic Compressibility of Carbon Nanotubes in the Wigner Crystal Regime. PHYSICAL REVIEW LETTERS 2019; 123:197701. [PMID: 31765201 DOI: 10.1103/physrevlett.123.197701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Indexed: 06/10/2023]
Abstract
Electronic compressibility, the second derivative of ground-state energy with respect to total electron number, is a measurable quantity that reveals the interaction strength of a system and can be used to characterize the orderly crystalline lattice of electrons known as the Wigner crystal. Here, we measure the electronic compressibility of individual suspended ultraclean carbon nanotubes in the low-density Wigner crystal regime. Using low-temperature quantum transport measurements, we determine the compressibility as a function of carrier number in nanotubes with varying band gaps. We observe two qualitatively different trends in compressibility versus carrier number, both of which can be explained using a theoretical model of a Wigner crystal that accounts for both the band gap and the confining potential experienced by charge carriers. We extract the interaction strength as a function of carrier number for individual nanotubes and show that the compressibility can be used to distinguish between strongly and weakly interacting regimes.
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Affiliation(s)
- Neda Lotfizadeh
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Daniel R McCulley
- Department of Physics, Oregon State University, Corvallis, Oregon 97331, USA
| | - Mitchell J Senger
- Department of Physics, Oregon State University, Corvallis, Oregon 97331, USA
| | - Han Fu
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - Ethan D Minot
- Department of Physics, Oregon State University, Corvallis, Oregon 97331, USA
| | - Brian Skinner
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - Vikram V Deshpande
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
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16
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Verbiest GJ, Janssen H, Xu D, Ge X, Goldsche M, Sonntag J, Khodkov T, Banszerus L, von den Driesch N, Buca D, Watanabe K, Taniguchi T, Stampfer C. Integrated impedance bridge for absolute capacitance measurements at cryogenic temperatures and finite magnetic fields. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:084706. [PMID: 31472650 DOI: 10.1063/1.5089207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 08/04/2019] [Indexed: 06/10/2023]
Abstract
We developed an impedance bridge that operates at cryogenic temperatures (down to 60 mK) and in perpendicular magnetic fields up to at least 12 T. This is achieved by mounting a GaAs HEMT amplifier perpendicular to a printed circuit board containing the device under test and thereby parallel to the magnetic field. The measured amplitude and phase of the output signal allows for the separation of the total impedance into an absolute capacitance and a resistance. Through a detailed noise characterization, we find that the best resolution is obtained when operating the HEMT amplifier at the highest gain. We obtained a resolution in the absolute capacitance of 6.4 aF/Hz at 77 K on a comb-drive actuator while maintaining a small excitation amplitude of 15 kBT/e. We show the magnetic field functionality of our impedance bridge by measuring the quantum Hall plateaus of a top-gated hBN/graphene/hBN heterostructure at 60 mK with a probe signal of 12.8 kBT/e.
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Affiliation(s)
- G J Verbiest
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
| | - H Janssen
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
| | - D Xu
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
| | - X Ge
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
| | - M Goldsche
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
| | - J Sonntag
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
| | - T Khodkov
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
| | - L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
| | - N von den Driesch
- Peter Grünberg Institute (PGI-8/9), Forschungszentrum Jülich, 52425 Jülich, Germany, EU
| | - D Buca
- Peter Grünberg Institute (PGI-8/9), Forschungszentrum Jülich, 52425 Jülich, Germany, EU
| | - K Watanabe
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
| | - T Taniguchi
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52056 Aachen, Germany, EU
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Piyanzina II, Eyert V, Lysogorskiy YV, Tayurskii DA, Kopp T. Oxygen vacancies and hydrogen doping in LaAlO 3/SrTiO 3 heterostructures: electronic properties and impact on surface and interface reconstruction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:295601. [PMID: 30970333 DOI: 10.1088/1361-648x/ab1831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We investigate the effect of oxygen vacancies and hydrogen dopants at the surface and inside slabs of [Formula: see text], [Formula: see text], and [Formula: see text]/[Formula: see text] heterostructures on the electronic properties by means of electronic structure calculations as based on density functional theory. Depending on the concentration, the presence of these defects in a [Formula: see text] slab can suppress the surface conductivity. In contrast, in insulating [Formula: see text] slabs already very small concentrations of oxygen vacancies or hydrogen dopant atoms induce a finite occupation of the conduction band. Surface defects in insulating [Formula: see text]/[Formula: see text] heterostructure slabs with three [Formula: see text] overlayers lead to the emergence of interface conductivity. Calculated defect formation energies reveal strong preference of hydrogen dopant atoms for surface sites for all structures and concentrations considered. Strong decrease of the defect formation energy of hydrogen adatoms with increasing thickness of the [Formula: see text] overlayer and crossover from positive to negative values, taken together with the metallic conductivity induced by hydrogen adatoms, seamlessly explains the semiconductor-metal transition observed for these heterostructures as a function of the overlayer thickness. Moreover, we show that the potential drop and concomitant shift of (layer resolved) band edges is suppressed for the metallic configuration. Finally, magnetism with stable local moments, which form atomically thin magnetic layers at the interface, is generated by oxygen vacancies either at the surface or the interface, or by hydrogen atoms buried at the interface. In particular, oxygen vacancies in the [Formula: see text] interface layer cause drastic downshift of the 3d e g states of the Ti atoms neighboring the vacancies, giving rise to strongly localized magnetic moments, which add to the two-dimensional background magnetization.
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Affiliation(s)
- I I Piyanzina
- Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany. Institute of Physics, Kazan Federal University, 420008 Kazan, Russia
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18
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Luo W, Boselli M, Poumirol JM, Ardizzone I, Teyssier J, van der Marel D, Gariglio S, Triscone JM, Kuzmenko AB. High sensitivity variable-temperature infrared nanoscopy of conducting oxide interfaces. Nat Commun 2019; 10:2774. [PMID: 31235858 PMCID: PMC6591405 DOI: 10.1038/s41467-019-10672-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 05/21/2019] [Indexed: 11/09/2022] Open
Abstract
Probing the local transport properties of two-dimensional electron systems (2DES) confined at buried interfaces requires a non-invasive technique with a high spatial resolution operating in a broad temperature range. In this paper, we investigate the scattering-type scanning near field optical microscopy as a tool for studying the conducting LaAlO3/SrTiO3 interface from room temperature down to 6 K. We show that the near-field optical signal, in particular its phase component, is highly sensitive to the transport properties of the electron system present at the interface. Our modeling reveals that such sensitivity originates from the interaction of the AFM tip with coupled plasmon-phonon modes with a small penetration depth. The model allows us to quantitatively correlate changes in the optical signal with the variation of the 2DES transport properties induced by cooling and by electrostatic gating. To probe the spatial resolution of the technique, we image conducting nano-channels written in insulating heterostructures with a voltage-biased tip of an atomic force microscope.
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Affiliation(s)
- Weiwei Luo
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Margherita Boselli
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Jean-Marie Poumirol
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Ivan Ardizzone
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Jérémie Teyssier
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Dirk van der Marel
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Stefano Gariglio
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Jean-Marc Triscone
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Alexey B Kuzmenko
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland.
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19
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Patwari J, Chatterjee A, Ghadi H, Sharma H, Chakrabarti S, Pal SK. In situ measurement of temperature dependent picosecond resolved carrier dynamics in near infrared (NIR) sensitive device on action. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:043909. [PMID: 31042972 DOI: 10.1063/1.5050951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 04/01/2019] [Indexed: 06/09/2023]
Abstract
The carrier dynamics study of emerging near infrared (NIR) absorbing materials is an essential need to develop device technology toward enhanced NIR light harvesting. In this study, we have documented the design of an indigenously developed time correlated single photoncounting (TCSPC) system working in the NIR (900 nm-1700 nm) spectral region. The system is compatible to study transient photoluminescence of device samples under tunable bias voltages. The liquid nitrogen cooling and electrical heating of the sample chamber provides additional flexibility of temperature dependent study starting from -196 °C to 400 °C. As a model system to study, we have chosen a multilayer InAs/InGaAs/GaAs/AlGaAs dot in the dual well device sample as the thin film quantum dot heterostructures are of huge relevance in various NIR harvesting devices. We have investigated the detail carrier dynamics of the device sample using the transient photoluminescence upon varying temperature (80 K-300 K), varying emission energy and different bias voltages (0 V-15 V). The critical temperature (160 K) and critical bias (12 V) of achieving longest excited state lifetime has been mechanistically explained using various competing photophysical phenomena such as hole diffusion, energy relaxation, etc. The emission wavelength dependent study at below and above critical temperature further provides an insight into the dominance of carrier capture and thermal escape at the two different temperature zones. Along with the detail understanding of the carrier dynamics, the results can be helpful to get an idea of the electrical stability of the device and the operability temperature as well. The reasonable good resolution of the NIR TCSPC system and considerable good results ensure the future application of the same for other devices also.
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Affiliation(s)
- Jayita Patwari
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Arka Chatterjee
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Hemant Ghadi
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Hemant Sharma
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Subhananda Chakrabarti
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Samir Kumar Pal
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
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Modeling of 2DEG characteristics of InxAl1−xN/AlN/GaN-Based HEMT Considering Polarization and Quantum Mechanical Effect. ELECTRONICS 2018. [DOI: 10.3390/electronics7120410] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A comprehensive model for 2DEG characteristics of InxAl1−xN/AlN/GaN heterostructure has been presented, taking both polarization and bulk ionized charge into account. Investigations on the 2DEG density and electron distribution across the heterostructure have been carried out using solutions of coupled 1-D Schrödinger-Poisson equations solved by an improved iterative scheme. The proposed model extends a previous approach allowing for estimating the quantum mechanical effect for a generic InAlN/GaN-based HEMT within the range of the Hartree approximation. A critical AlN thickness (~2.28 nm) is predicted when considering the 2DEG density in dependence on a lattice matched In0.17Al0.83N thickness. The obtained results present in this work provide a guideline for the experimental observation of the subband structure of InAlN/GaN heterostructure and may be used as a design tool for the optimization of that epilayer structure.
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21
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Majorana Fermions in One-Dimensional Structures at LaAlO3/SrTiO3 Oxide Interfaces. CONDENSED MATTER 2018. [DOI: 10.3390/condmat3040037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We study one-dimensional structures that may be formed at the LaAlO 3 /SrTiO 3 oxide interface by suitable top gating. These structures are modeled via a single-band model with Rashba spin-orbit coupling, superconductivity and a magnetic field along the one-dimensional chain. We first discuss the conditions for the occurrence of a topological superconducting phase and the related formation of Majorana fermions at the chain endpoints, highlighting a close similarity between this model and the Kitaev model, which also reflects in a similar condition the formation of a topological phase. Solving the model in real space, we also study the spatial extension of the wave function of the Majorana fermions and how this increases with approaching the limit condition for the topological state. Using a scattering matrix formalism, we investigate the stability of the Majorana fermions in the presence of disorder and discuss the evolution of the topological phase with increasing disorder.
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22
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Wang Z, Zhong Z, McKeown Walker S, Ristic Z, Ma JZ, Bruno FY, Riccò S, Sangiovanni G, Eres G, Plumb NC, Patthey L, Shi M, Mesot J, Baumberger F, Radovic M. Atomically Precise Lateral Modulation of a Two-Dimensional Electron Liquid in Anatase TiO 2 Thin Films. NANO LETTERS 2017; 17:2561-2567. [PMID: 28282495 DOI: 10.1021/acs.nanolett.7b00317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic structure of an oxide surface 2DEL demonstrating the lateral modulation of electronic states with atomic scale precision on an unprecedented length scale comparable to the Fermi wavelength. To this end, we use pulsed laser deposition to grow anatase TiO2 films terminated by a (1 × 4) in-plane surface reconstruction. Employing photostimulated chemical surface doping we induce 2DELs with tunable carrier densities that are confined within a few TiO2 layers below the surface. Subsequent in situ angle-resolved photoemission experiments demonstrate that the (1 × 4) surface reconstruction provides a periodic lateral perturbation of the electron liquid. This causes strong backfolding of the electronic bands, opening of unidirectional gaps and a saddle point singularity in the density of states near the chemical potential.
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Affiliation(s)
- Z Wang
- Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
- Department of Quantum Matter Physics, University of Geneva , 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Z Zhong
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg , Am Hubland, Würzburg 97070 Germany
| | - S McKeown Walker
- Department of Quantum Matter Physics, University of Geneva , 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Z Ristic
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - J-Z Ma
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China
| | - F Y Bruno
- Department of Quantum Matter Physics, University of Geneva , 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - S Riccò
- Department of Quantum Matter Physics, University of Geneva , 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - G Sangiovanni
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg , Am Hubland, Würzburg 97070 Germany
| | - G Eres
- Materials Science and Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
| | - L Patthey
- Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
- SwissFEL, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich , CH-8093 Zürich, Switzerland
| | - F Baumberger
- Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
- Department of Quantum Matter Physics, University of Geneva , 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
- SwissFEL, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
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23
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Iida K, Noda M, Nobusada K. Development of theoretical approach for describing electronic properties of hetero-interface systems under applied bias voltage. J Chem Phys 2017; 146:084706. [PMID: 28249433 DOI: 10.1063/1.4976970] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We have developed a theoretical approach for describing the electronic properties of hetero-interface systems under an applied electrode bias. The finite-temperature density functional theory is employed for controlling the chemical potential in their interfacial region, and thereby the electronic charge of the system is obtained. The electric field generated by the electronic charging is described as a saw-tooth-like electrostatic potential. Because of the continuum approximation of dielectrics sandwiched between electrodes, we treat dielectrics with thicknesses in a wide range from a few nanometers to more than several meters. Furthermore, the approach is implemented in our original computational program named grid-based coupled electron and electromagnetic field dynamics (GCEED), facilitating its application to nanostructures. Thus, the approach is capable of comprehensively revealing electronic structure changes in hetero-interface systems with an applied bias that are practically useful for experimental studies. We calculate the electronic structure of a SiO2-graphene-boron nitride (BN) system in which an electrode bias is applied between the graphene layer and an electrode attached on the SiO2 film. The electronic energy barrier between graphene and BN is varied with an applied bias, and the energy variation depends on the thickness of the BN film. This is because the density of states of graphene is so low that the graphene layer cannot fully screen the electric field generated by the electrodes. We have demonstrated that the electronic properties of hetero-interface systems are well controlled by the combination of the electronic charging and the generated electric field.
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Affiliation(s)
- Kenji Iida
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan
| | - Masashi Noda
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan
| | - Katsuyuki Nobusada
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan
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24
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Liu HJ, Lin JC, Fang YW, Wang JC, Huang BC, Gao X, Huang R, Dean PR, Hatton PD, Chin YY, Lin HJ, Chen CT, Ikuhara Y, Chiu YP, Chang CS, Duan CG, He Q, Chu YH. A Metal-Insulator Transition of the Buried MnO 2 Monolayer in Complex Oxide Heterostructure. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:9142-9151. [PMID: 27571277 DOI: 10.1002/adma.201602281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 07/10/2016] [Indexed: 06/06/2023]
Abstract
A novel artificially created MnO2 monolayer system is demonstrated in atomically controlled epitaxial perovskite heterostructures. With careful design of different electrostatic boundary conditions, a magnetic transition as well as a metal-insulator transition of the MnO2 monolayer is unveiled, providing a fundamental understanding of dimensionality-confined strongly correlated electron systems and a direction to design new electronic devices.
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Affiliation(s)
- Heng-Jui Liu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan
- Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan
| | - Jheng-Cyuan Lin
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
| | - Yue-Wen Fang
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, 200241, China
| | - Jing-Ching Wang
- Department of Physics, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Bo-Chao Huang
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
| | - Xiang Gao
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, 456-8587, Japan
| | - Rong Huang
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, 200241, China
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, 456-8587, Japan
| | - Philip R Dean
- Department of Physics, Durham University, Durham DH1 3LE, UK
| | - Peter D Hatton
- Department of Physics, Durham University, Durham DH1 3LE, UK
| | - Yi-Ying Chin
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Hong-Ji Lin
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Chien-Te Chen
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Yuichi Ikuhara
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, 456-8587, Japan
- Institute of Engineering Innovation, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Ya-Ping Chiu
- Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan
- Department of Physics, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Chia-Seng Chang
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
| | - Chun-Gang Duan
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, 200241, China
| | - Qing He
- Department of Physics, Durham University, Durham DH1 3LE, UK.
| | - Ying-Hao Chu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan.
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan.
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25
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Chen Z, Yuan H, Xie Y, Lu D, Inoue H, Hikita Y, Bell C, Hwang HY. Dual-Gate Modulation of Carrier Density and Disorder in an Oxide Two-Dimensional Electron System. NANO LETTERS 2016; 16:6130-6136. [PMID: 27605459 DOI: 10.1021/acs.nanolett.6b02348] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Carrier density and disorder are two crucial parameters that control the properties of correlated two-dimensional electron systems. In order to disentangle their individual contributions to quantum phenomena, independent tuning of these two parameters is required. Here, by utilizing a hybrid liquid/solid electric dual-gate geometry acting on the conducting LaAlO3/SrTiO3 heterointerface, we obtain an additional degree of freedom to strongly modify the electron confinement profile and thus the strength of interfacial scattering, independent from the carrier density. A dual-gate controlled nonlinear Hall effect is a direct manifestation of this profile, which can be quantitatively understood by a Poisson-Schrödinger sub-band model. In particular, the large nonlinear dielectric response of SrTiO3 enables a very wide range of tunable density and disorder, far beyond that for conventional semiconductors. Our study provides a broad framework for understanding various reported phenomena at the LaAlO3/SrTiO3 interface.
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Affiliation(s)
- Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
| | - Hongtao Yuan
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Yanwu Xie
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Di Lu
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
| | - Hisashi Inoue
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Christopher Bell
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- H.H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
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26
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Lee PW, Singh VN, Guo GY, Liu HJ, Lin JC, Chu YH, Chen CH, Chu MW. Hidden lattice instabilities as origin of the conductive interface between insulating LaAlO3 and SrTiO3. Nat Commun 2016; 7:12773. [PMID: 27624682 PMCID: PMC5027288 DOI: 10.1038/ncomms12773] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 08/01/2016] [Indexed: 11/09/2022] Open
Abstract
The metallic interface between insulating LaAlO3 and SrTiO3 opens up the field of oxide electronics. With more than a decade of researches on this heterostructure, the origin of the interfacial conductivity, however, remains unsettled. Here we resolve this long-standing puzzle by atomic-scale observation of electron-gas formation for screening hidden lattice instabilities, rejuvenated near the interface by epitaxial strain. Using atomic-resolution imaging and electron spectroscopy, the generally accepted notions of polar catastrophe and cation intermixing for the metallic interface are discounted. Instead, the conductivity onset at the critical thickness of 4-unit cell LaAlO3 on SrTiO3 substrate is accompanied with head-to-head ferroelectric-like polarizations across the interface due to strain-rejuvenated ferroelectric-like instabilities in the materials. The divergent depolarization fields of the head-to-head polarizations cast the interface into an electron reservoir, forming screening electron gas in SrTiO3 with LaAlO3 hosting complementary localized holes. The ferroelectric-like polarizations and electron–hole juxtaposition reveal the cooperative nature of metallic LaAlO3/SrTiO3. The origin of interfacial conductivity between two insulating oxides, LaAlO3 and SrTiO3, remains elusive despite a long time research. Here, Lee et al. report atomic-scale observation of electron-gas formation for screening hidden ferroelectric-like lattice instabilities, discounting the role of polar catastrophe and cation intermixing.
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Affiliation(s)
- P W Lee
- Department of Physics, National Taiwan University, Taipei 106, Taiwan.,Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan
| | - V N Singh
- Department of Physics, National Taiwan University, Taipei 106, Taiwan.,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | - G Y Guo
- Department of Physics, National Taiwan University, Taipei 106, Taiwan.,Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan
| | - H-J Liu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan
| | - J-C Lin
- Institute of Physics, Academia Sinica, Taipei 105, Taiwan
| | - Y-H Chu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan.,Institute of Physics, Academia Sinica, Taipei 105, Taiwan
| | - C H Chen
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan.,Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - M-W Chu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan
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27
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Kumar N, Kitoh A, Inoue IH. Anomalous enhancement of the sheet carrier density beyond the classic limit on a SrTiO3 surface. Sci Rep 2016; 6:25789. [PMID: 27174141 PMCID: PMC4865841 DOI: 10.1038/srep25789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/22/2016] [Indexed: 11/28/2022] Open
Abstract
Electrostatic carrier accumulation on an insulating (100) surface of SrTiO3 by fabricating a field effect transistor with Parylene-C (6 nm)/HfO2 (20 nm) bilayer gate insulator has revealed a mystifying phenomenon: sheet carrier density is about 10 times as large as ( is the sheet capacitance of the gate insulator, VG is the gate voltage, and e is the elementary charge). The channel is so clean to exhibit small subthreshod swing of 170 mV/decade and large mobility of 11 cm2/Vs for of 1 × 1014 cm−2 at room temperature. Since does not depend on either VG nor time duration, beyond is solely ascribed to negative charge compressibility of the carriers, which was in general considered as due to exchange interactions among electrons in the small limit. However, the observed is too large to be naively understood by the framework. Alternative ideas are proposed in this work.
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Affiliation(s)
- Neeraj Kumar
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Ai Kitoh
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Isao H Inoue
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
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28
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Fallahazad B, Movva HCP, Kim K, Larentis S, Taniguchi T, Watanabe K, Banerjee SK, Tutuc E. Shubnikov-de Haas Oscillations of High-Mobility Holes in Monolayer and Bilayer WSe_{2}: Landau Level Degeneracy, Effective Mass, and Negative Compressibility. PHYSICAL REVIEW LETTERS 2016; 116:086601. [PMID: 26967432 DOI: 10.1103/physrevlett.116.086601] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Indexed: 06/05/2023]
Abstract
We study the magnetotransport properties of high-mobility holes in monolayer and bilayer WSe_{2}, which display well defined Shubnikov-de Haas (SdH) oscillations, and quantum Hall states in high magnetic fields. In both mono- and bilayer WSe_{2}, the SdH oscillations and the quantum Hall states occur predominantly at even filling factors, evincing a twofold Landau level degeneracy. The Fourier transform analysis of the SdH oscillations in bilayer WSe_{2} reveals the presence of two subbands localized in the top or the bottom layer, as well as negative compressibility. From the temperature dependence of the SdH oscillations we determine a hole effective mass of 0.45m_{0} for both mono- and bilayer WSe_{2}.
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Affiliation(s)
- Babak Fallahazad
- Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Hema C P Movva
- Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Kyounghwan Kim
- Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Stefano Larentis
- Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Takashi Taniguchi
- National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Kenji Watanabe
- National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Sanjay K Banerjee
- Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Emanuel Tutuc
- Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA
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29
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Bakaul SR, Serrao CR, Lee M, Yeung CW, Sarker A, Hsu SL, Yadav AK, Dedon L, You L, Khan AI, Clarkson JD, Hu C, Ramesh R, Salahuddin S. Single crystal functional oxides on silicon. Nat Commun 2016; 7:10547. [PMID: 26853112 PMCID: PMC4748113 DOI: 10.1038/ncomms10547] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 12/24/2015] [Indexed: 11/26/2022] Open
Abstract
Single-crystalline thin films of complex oxides show a rich variety of functional properties such as ferroelectricity, piezoelectricity, ferro and antiferromagnetism and so on that have the potential for completely new electronic applications. Direct synthesis of such oxides on silicon remains challenging because of the fundamental crystal chemistry and mechanical incompatibility of dissimilar interfaces. Here we report integration of thin (down to one unit cell) single crystalline, complex oxide films onto silicon substrates, by epitaxial transfer at room temperature. In a field-effect transistor using a transferred lead zirconate titanate layer as the gate insulator, we demonstrate direct reversible control of the semiconductor channel charge with polarization state. These results represent the realization of long pursued but yet to be demonstrated single-crystal functional oxides on-demand on silicon. Synthesis of single-crystal complex-oxide films directly on silicon is difficult due to differing interfacial chemistry. Here, the authors demonstrate room-temperature integration of single-crystal lead zirconate titanate on to silicon to act as a gate insulator in a field-effect transistor.
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Affiliation(s)
- Saidur Rahman Bakaul
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA
| | - Claudy Rayan Serrao
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA.,Department of Material Science and Engineering, University of California, Berkeley, California, USA
| | - Michelle Lee
- Department of Physics, University of California, Berkeley, California, USA
| | - Chun Wing Yeung
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA
| | - Asis Sarker
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA
| | - Shang-Lin Hsu
- Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Ajay Kumar Yadav
- Department of Material Science and Engineering, University of California, Berkeley, California, USA
| | - Liv Dedon
- Department of Material Science and Engineering, University of California, Berkeley, California, USA
| | - Long You
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA
| | - Asif Islam Khan
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA
| | - James David Clarkson
- Department of Material Science and Engineering, University of California, Berkeley, California, USA
| | - Chenming Hu
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA
| | - Ramamoorthy Ramesh
- Department of Material Science and Engineering, University of California, Berkeley, California, USA.,Department of Physics, University of California, Berkeley, California, USA.,Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Sayeef Salahuddin
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA.,Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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30
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Lin JC, Tra VT, Tsai DS, Lin TT, Huang PC, Hsu WL, Wu HJ, Huang R, Van Chien N, Yoshida R, Lin JY, Ikuhara Y, Chiu YP, Gwo S, Tsai DP, He JH, Chu YH. Control of the Metal-Insulator Transition at Complex Oxide Heterointerfaces through Visible Light. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:764-770. [PMID: 26607052 DOI: 10.1002/adma.201503499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 10/14/2015] [Indexed: 06/05/2023]
Abstract
The coupling of the localized surface plasmon resonance of Au nanoparticles is utilized to deliver a visible-light stimulus to control conduction at the LaAlO3 /SrTiO3 interface. A giant photoresponse and the controllable metal-insulator transition are characterized at this heterointerface. This study paves a new route to optical control of the functionality at the heterointerfaces.
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Affiliation(s)
- Jheng-Cyuan Lin
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
| | - Vu Thanh Tra
- Institute of Physics, National Chiao Tung University, Hsinchu, 30010, Taiwan
| | - Dung-Sheng Tsai
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, 10617, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Tai-Te Lin
- Department of Physics, National Sun Yat-sen University, Kaohsiung, 804, Taiwan
| | - Po-Cheng Huang
- Department of Physics, National Sun Yat-sen University, Kaohsiung, 804, Taiwan
| | - Wei-Lun Hsu
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Hui Jun Wu
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Rong Huang
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, 200062, China
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, 456-8587, Japan
| | - Nguyen Van Chien
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan
| | - Ryuji Yoshida
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, 456-8587, Japan
| | - Jiunn-Yuan Lin
- Institute of Physics, National Chiao Tung University, Hsinchu, 30010, Taiwan
| | - Yuichi Ikuhara
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, 456-8587, Japan
- Institute of Engineering Innovation, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Ya-Ping Chiu
- Department of Physics, National Sun Yat-sen University, Kaohsiung, 804, Taiwan
- Department of Physics, National Taiwan Normal University, Taipei, 116, Taiwan
| | - Shangjr Gwo
- Department of Physics, National Tsing-Hua University, Hsinchu, 30013, Taiwan
| | - Din Ping Tsai
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Jr-Hau He
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, 10617, Taiwan
- Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Ying-Hao Chu
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan
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31
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Kasamatsu S, Watanabe S, Hwang CS, Han S. Emergence of Negative Capacitance in Multidomain Ferroelectric-Paraelectric Nanocapacitors at Finite Bias. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:335-340. [PMID: 26568333 DOI: 10.1002/adma.201502916] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 10/01/2015] [Indexed: 06/05/2023]
Abstract
The emergence of negative capacitance in an ultrathin ferroelectric/paraelectric bilayer capacitor under electrical bias is examined using first-principles simulation. An antiferroelectric-like behavior is predicted, and negative capacitance is shown to emerge when the monodomain state becomes stable after bias application. The polydomain-monodomain transition is also shown to be a source of capacitance enhancement.
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Affiliation(s)
- Shusuke Kasamatsu
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba, 277-8581, Japan
| | - Satoshi Watanabe
- Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Cheol Seong Hwang
- Department of Materials Science and Engineering and Inter-university Semiconductor Research Center, Seoul National University, Seoul, 151-742, South Korea
| | - Seungwu Han
- Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742, South Korea
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32
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Riley JM, Meevasana W, Bawden L, Asakawa M, Takayama T, Eknapakul T, Kim TK, Hoesch M, Mo SK, Takagi H, Sasagawa T, Bahramy MS, King PDC. Negative electronic compressibility and tunable spin splitting in WSe2. NATURE NANOTECHNOLOGY 2015; 10:1043-1047. [PMID: 26389661 DOI: 10.1038/nnano.2015.217] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 08/20/2015] [Indexed: 06/05/2023]
Abstract
Tunable bandgaps, extraordinarily large exciton-binding energies, strong light-matter coupling and a locking of the electron spin with layer and valley pseudospins have established transition-metal dichalcogenides (TMDs) as a unique class of two-dimensional (2D) semiconductors with wide-ranging practical applications. Using angle-resolved photoemission (ARPES), we show here that doping electrons at the surface of the prototypical strong spin-orbit TMD WSe2, akin to applying a gate voltage in a transistor-type device, induces a counterintuitive lowering of the surface chemical potential concomitant with the formation of a multivalley 2D electron gas (2DEG). These measurements provide a direct spectroscopic signature of negative electronic compressibility (NEC), a result of electron-electron interactions, which we find persists to carrier densities approximately three orders of magnitude higher than in typical semiconductor 2DEGs that exhibit this effect. An accompanying tunable spin splitting of the valence bands further reveals a complex interplay between single-particle band-structure evolution and many-body interactions in electrostatically doped TMDs. Understanding and exploiting this will open up new opportunities for advanced electronic and quantum-logic devices.
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Affiliation(s)
- J M Riley
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - W Meevasana
- School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
- NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - L Bawden
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
| | - M Asakawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - T Takayama
- Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033, Japan
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - T Eknapakul
- School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - S-K Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley California 94720, USA
| | - H Takagi
- Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033, Japan
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - T Sasagawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - M S Bahramy
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
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33
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He J, Hogan T, Mion TR, Hafiz H, He Y, Denlinger JD, Mo SK, Dhital C, Chen X, Lin Q, Zhang Y, Hashimoto M, Pan H, Lu DH, Arita M, Shimada K, Markiewicz RS, Wang Z, Kempa K, Naughton MJ, Bansil A, Wilson SD, He RH. Spectroscopic evidence for negative electronic compressibility in a quasi-three-dimensional spin-orbit correlated metal. NATURE MATERIALS 2015; 14:577-582. [PMID: 25915033 DOI: 10.1038/nmat4273] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 03/19/2015] [Indexed: 06/04/2023]
Abstract
Negative compressibility is a sign of thermodynamic instability of open or non-equilibrium systems. In quantum materials consisting of multiple mutually coupled subsystems, the compressibility of one subsystem can be negative if it is countered by positive compressibility of the others. Manifestations of this effect have so far been limited to low-dimensional dilute electron systems. Here, we present evidence from angle-resolved photoemission spectroscopy (ARPES) for negative electronic compressibility (NEC) in the quasi-three-dimensional (3D) spin-orbit correlated metal (Sr1-xLax)3Ir2O7. Increased electron filling accompanies an anomalous decrease of the chemical potential, as indicated by the overall movement of the deep valence bands. Such anomaly, suggestive of NEC, is shown to be primarily driven by the lowering in energy of the conduction band as the correlated bandgap reduces. Our finding points to a distinct pathway towards an uncharted territory of NEC featuring bulk correlated metals with unique potential for applications in low-power nanoelectronics and novel metamaterials.
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Affiliation(s)
- Junfeng He
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - T Hogan
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Thomas R Mion
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - H Hafiz
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
| | - Y He
- Stanford Synchrotron Radiation Lightsource &Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - J D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - S-K Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C Dhital
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - X Chen
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Qisen Lin
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Y Zhang
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - M Hashimoto
- Stanford Synchrotron Radiation Lightsource &Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - H Pan
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - D H Lu
- Stanford Synchrotron Radiation Lightsource &Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - M Arita
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Hiroshima 739-0046, Japan
| | - K Shimada
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Hiroshima 739-0046, Japan
| | - R S Markiewicz
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
| | - Z Wang
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - K Kempa
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - M J Naughton
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - A Bansil
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
| | - S D Wilson
- 1] Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA [2] Materials Department, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Rui-Hua He
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
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34
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Pallecchi I, Telesio F, Li D, Fête A, Gariglio S, Triscone JM, Filippetti A, Delugas P, Fiorentini V, Marré D. Giant oscillating thermopower at oxide interfaces. Nat Commun 2015; 6:6678. [PMID: 25813265 PMCID: PMC4389223 DOI: 10.1038/ncomms7678] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 02/18/2015] [Indexed: 11/09/2022] Open
Abstract
Understanding the nature of charge carriers at the LaAlO3/SrTiO3 interface is one of the major open issues in the full comprehension of the charge confinement phenomenon in oxide heterostructures. Here, we investigate thermopower to study the electronic structure in LaAlO3/SrTiO3 at low temperature as a function of gate field. In particular, under large negative gate voltage, corresponding to the strongly depleted charge density regime, thermopower displays high negative values of the order of 10(4)-10(5) μVK(-1), oscillating at regular intervals as a function of the gate voltage. The huge thermopower magnitude can be attributed to the phonon-drag contribution, while the oscillations map the progressive depletion and the Fermi level descent across a dense array of localized states lying at the bottom of the Ti 3d conduction band. This study provides direct evidence of a localized Anderson tail in the two-dimensional electron liquid at the LaAlO3/SrTiO3 interface.
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Affiliation(s)
- Ilaria Pallecchi
- Department of Physics, CNR-SPIN and Genova University, via Dodecaneso 33, Genova 16146, Italy
| | - Francesca Telesio
- Department of Physics, CNR-SPIN and Genova University, via Dodecaneso 33, Genova 16146, Italy
| | - Danfeng Li
- Department of Quantum Matter Physics,, University of Geneva, 24 Quai E.-Ansermet, Geneva 4 1211, Switzerland
| | - Alexandre Fête
- Department of Quantum Matter Physics,, University of Geneva, 24 Quai E.-Ansermet, Geneva 4 1211, Switzerland
| | - Stefano Gariglio
- Department of Quantum Matter Physics,, University of Geneva, 24 Quai E.-Ansermet, Geneva 4 1211, Switzerland
| | - Jean-Marc Triscone
- Department of Quantum Matter Physics,, University of Geneva, 24 Quai E.-Ansermet, Geneva 4 1211, Switzerland
| | - Alessio Filippetti
- CNR-IOM UOS Cagliari, c/o Dipartimento di Fisica, Università di Cagliari, S.P. Monserrato-Sestu Km.0,700, Monserrato (Ca) 09042, Italy
| | - Pietro Delugas
- CompuNet, Istituto Italiano di Tecnologia—IIT, Via Morego 30, Genova 16163, Italy
| | - Vincenzo Fiorentini
- Dipartimento di Fisica, Università di Cagliari, CNR-IOM, S.P. Monserrato-Sestu Km.0,700, Monserrato (Ca) 09042, Italy
| | - Daniele Marré
- Department of Physics, CNR-SPIN and Genova University, via Dodecaneso 33, Genova 16146, Italy
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35
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Khan AI, Chatterjee K, Wang B, Drapcho S, You L, Serrao C, Bakaul SR, Ramesh R, Salahuddin S. Negative capacitance in a ferroelectric capacitor. NATURE MATERIALS 2015; 14:182-186. [PMID: 25502099 DOI: 10.1038/nmat4148] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 10/24/2014] [Indexed: 06/04/2023]
Abstract
The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time--in exactly the opposite direction to which voltage for a regular capacitor should change. Analysis of this 'inductance'-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications.
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Affiliation(s)
- Asif Islam Khan
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Korok Chatterjee
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Brian Wang
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Steven Drapcho
- Department of Physics, University of California, Berkeley, California 94270, USA
| | - Long You
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Claudy Serrao
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Saidur Rahman Bakaul
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - Ramamoorthy Ramesh
- 1] Department of Physics, University of California, Berkeley, California 94270, USA [2] Department of Material Science and Engineering, University of California, Berkeley, California 94270, USA [3] Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94270, USA
| | - Sayeef Salahuddin
- 1] Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA [2] Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94270, USA
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36
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Kim SK, Kim SI, Lim H, Jeong DS, Kwon B, Baek SH, Kim JS. Electric-field-induced shift in the threshold voltage in LaAlO3/SrTiO3 heterostructures. Sci Rep 2015; 5:8023. [PMID: 25620684 PMCID: PMC4306114 DOI: 10.1038/srep08023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 12/30/2014] [Indexed: 11/09/2022] Open
Abstract
The two-dimensional electron gas (2DEG) at the interface between insulating LaAlO3 and SrTiO3 is intriguing both as a fundamental science topic and for possible applications in electronics or sensors. For example, because the electrical conductance of the 2DEG at the LaAlO3/SrTiO3 interface can be tuned by applying an electric field, new electronic devices utilizing the 2DEG at the LaAlO3/SrTiO3 interface could be possible. For the implementation of field-effect devices utilizing the 2DEG, determining the on/off switching voltage for the devices and ensuring their stability are essential. However, the factors influencing the threshold voltage have not been extensively investigated. Here, we report the voltage-induced shift of the threshold voltage of Pt/LaAlO3/SrTiO3 heterostructures. A large negative voltage induces an irreversible positive shift in the threshold voltage. In fact, after the application of such a large negative voltage, the original threshold voltage cannot be recovered even by application of a large positive electric field. This irreversibility is attributed to the generation of deep traps near the LaAlO3/SrTiO3 interface under the negative voltage. This finding could contribute to the implementation of nanoelectronic devices using the 2DEG at the LaAlO3/SrTiO3 interface.
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Affiliation(s)
- Seong Keun Kim
- 1] Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea [2] Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon, 305-333, Republic of Korea
| | - Shin-Ik Kim
- 1] Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea [2] Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon, 305-333, Republic of Korea
| | - Hyungkwang Lim
- 1] Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea [2] Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, South Korea
| | - Doo Seok Jeong
- 1] Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea [2] Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon, 305-333, Republic of Korea
| | - Beomjin Kwon
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea
| | - Seung-Hyub Baek
- 1] Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea [2] Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon, 305-333, Republic of Korea
| | - Jin-Sang Kim
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea
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37
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Srisonphan S, Hongesombut K. Tuning the ballistic electron transport of spatial graphene–metal sandwich electrode on a vacuum-silicon-based device. RSC Adv 2015. [DOI: 10.1039/c4ra09503k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Future high-speed electronic devices rely on the integration of hot-carrier generation and short transit time. The combination of a graphene–metal electrode can enable an extremely high ballistic electron emission bias to the graphene mesh at ambient conditions.
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Affiliation(s)
- Siwapon Srisonphan
- Department of Electrical Engineering
- Faculty of Engineering
- Kasetsart University
- Bangkok 10900
- Thailand
| | - Komsan Hongesombut
- Department of Electrical Engineering
- Faculty of Engineering
- Kasetsart University
- Bangkok 10900
- Thailand
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38
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Hanlumyuang Y, Li X, Sharma P. Mechanical strain can switch the sign of quantum capacitance from positive to negative. Phys Chem Chem Phys 2014; 16:22962-7. [PMID: 25259466 DOI: 10.1039/c4cp03131h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Quantum capacitance is a fundamental quantity that can directly reveal many-body interactions among electrons and is expected to play a critical role in nanoelectronics. One of the many tantalizing recent physical revelations about quantum capacitance is that it can possess a negative value, hence allowing for the possibility of enhancing the overall capacitance in some particular material systems beyond the scaling predicted by classical electrostatics. Using detailed quantum mechanical simulations, we found an intriguing result that mechanical strains can tune both signs and values of quantum capacitance. We used a small coaxially gated carbon nanotube as a paradigmatical capacitor system and showed that, for the range of mechanical strain considered, quantum capacitance can be adjusted from very large positive to very large negative values (in the order of plus/minus hundreds of attofarads), compared to the corresponding classical geometric value (0.31035 aF). This finding opens novel avenues in designing quantum capacitance for applications in nanosensors, energy storage, and nanoelectronics.
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Affiliation(s)
- Yuranan Hanlumyuang
- Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Bangkok, 10900, Thailand
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39
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Joung JG, Kim SI, Moon SY, Kim DH, Gwon HJ, Hong SH, Chang HJ, Hwang JH, Kwon BJ, Kim SK, Choi JW, Yoon SJ, Kang CY, Yoo KS, Kim JS, Baek SH. Nonvolatile resistance switching on two-dimensional electron gas. ACS APPLIED MATERIALS & INTERFACES 2014; 6:17785-17791. [PMID: 25243475 DOI: 10.1021/am504354c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Two-dimensional electron gas (2DEG) at the complex oxide interfaces have brought about considerable interest for the application of the next-generation multifunctional oxide electronics due to the exotic properties that do not exist in the bulk. In this study, we report the integration of 2DEG into the nonvolatile resistance switching cell as a bottom electrode, where the metal-insulator transition of 2DEG by an external field serves to significantly reduce the OFF-state leakage current while enhancing the on/off ratio. Using the Pt/Ta2O5-y/Ta2O5-x/SrTiO3 heterostructure as a model system, we demonstrate the nonvolatile resistance switching memory cell with a large on/off ratio (>10(6)) and a low leakage current at the OFF state (∼10(-13) A). Beyond exploring nonvolatile memory, our work also provides an excellent framework for exploring the fundamental understanding of novel physics in which electronic and ionic processes are coupled in the complex heterostructures.
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Affiliation(s)
- Jin Gwan Joung
- Electronic Materials Research Center, Korea Institute of Science and Technology , Seoul 136-791, Republic of Korea
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40
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Gao W, Khan A, Marti X, Nelson C, Serrao C, Ravichandran J, Ramesh R, Salahuddin S. Room-temperature negative capacitance in a ferroelectric-dielectric superlattice heterostructure. NANO LETTERS 2014; 14:5814-5819. [PMID: 25244689 DOI: 10.1021/nl502691u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate room-temperature negative capacitance in a ferroelectric-dielectric superlattice heterostructure. In epitaxially grown superlattice of ferroelectric BSTO (Ba0.8Sr0.2TiO3) and dielectric LAO (LaAlO3), capacitance was found to be larger compared to the constituent LAO (dielectric) capacitance. This enhancement of capacitance in a series combination of two capacitors indicates that the ferroelectric was stabilized in a state of negative capacitance. Negative capacitance was observed for superlattices grown on three different substrates (SrTiO3 (001), DyScO3 (110), and GdScO3 (110)) covering a large range of substrate strain. This demonstrates the robustness of the effect as well as potential for controlling the negative capacitance effect using epitaxial strain. Room-temperature demonstration of negative capacitance is an important step toward lowering the subthreshold swing in a transistor below the intrinsic thermodynamic limit of 60 mV/decade and thereby improving energy efficiency.
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Affiliation(s)
- Weiwei Gao
- Department of Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
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41
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Levy A, Bi F, Huang M, Lu S, Tomczyk M, Cheng G, Irvin P, Levy J. Writing and low-temperature characterization of oxide nanostructures. J Vis Exp 2014. [PMID: 25080268 PMCID: PMC4220744 DOI: 10.3791/51886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.
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Affiliation(s)
- Akash Levy
- Department of Physics, University of Pittsburgh;
| | - Feng Bi
- Department of Physics, University of Pittsburgh
| | | | - Shicheng Lu
- Department of Physics, University of Pittsburgh
| | | | | | | | - Jeremy Levy
- Department of Physics, University of Pittsburgh
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42
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Suppression of the critical thickness threshold for conductivity at the LaAlO3/SrTiO3 interface. Nat Commun 2014; 5:4291. [DOI: 10.1038/ncomms5291] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 06/04/2014] [Indexed: 11/09/2022] Open
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43
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Shi G, Hanlumyuang Y, Liu Z, Gong Y, Gao W, Li B, Kono J, Lou J, Vajtai R, Sharma P, Ajayan PM. Boron nitride-graphene nanocapacitor and the origins of anomalous size-dependent increase of capacitance. NANO LETTERS 2014; 14:1739-1744. [PMID: 24640945 DOI: 10.1021/nl4037824] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Conventional wisdom suggests that decreasing dimensions of dielectric materials (e.g., thickness of a film) should yield increasing capacitance. However, the quantum capacitance and the so-called "dead-layer" effect often conspire to decrease the capacitance of extremely small nanostructures, which is in sharp contrast to what is expected from classical electrostatics. Very recently, first-principles studies have predicted that a nanocapacitor made of graphene and hexagonal boron nitride (h-BN) films can achieve superior capacitor properties. In this work, we fabricate the thinnest possible nanocapacitor system, essentially consisting of only monolayer materials: h-BN with graphene electrodes. We experimentally demonstrate an increase of the h-BN films' permittivity in different stack structures combined with graphene. We find a significant increase in capacitance below a thickness of ∼5 nm, more than 100% of what is predicted by classical electrostatics. Detailed quantum mechanical calculations suggest that this anomalous increase in capacitance is due to the negative quantum capacitance that this particular materials system exhibits.
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Affiliation(s)
- Gang Shi
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
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44
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Space charge neutralization by electron-transparent suspended graphene. Sci Rep 2014; 4:3764. [PMID: 24441774 PMCID: PMC3895874 DOI: 10.1038/srep03764] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 12/27/2013] [Indexed: 11/23/2022] Open
Abstract
Graphene possesses many fascinating properties originating from the manifold potential for interactions at electronic, atomic, or molecular levels. Here we report measurement of electron transparency and hole charge induction response of a suspended graphene anode on top of a void channel formed in a SiO2/Si substrate. A two-dimensional (2D) electron gas induced at the oxide interface emits into air and makes a ballistic transport toward the suspended graphene. A small fraction (>~0.1%) of impinging electrons are captured at the edge of 2D hole system in graphene, demonstrating good transparency to very low energy (<3 eV) electrons. The hole charges induced in the suspended graphene anode have the effect of neutralizing the electron space charge in the void channel. This charge compensation dramatically enhances 2D electron gas emission at cathode to the level far surpassing the Child-Langmuir's space-charge-limited emission.
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45
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Singh MB, Kant R. Shape- and size-dependent electronic capacitance in nanostructured materials. Proc Math Phys Eng Sci 2013. [DOI: 10.1098/rspa.2013.0163] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The shape and size are the two important geometrical factors that affect the electronic screening in nano-materials. Here, we develop an analytical theory for electronic capacitance based on Thomas–Fermi screening in conjunction with ‘multiple scattering method’ for arbitrary-shaped nanostructures including electronic spillover correction. We relate the electronic capacitance of the material to the curvature correction expressed in terms of ratio of electronic screening length to principal radii of curvature. Electronic capacitance of various nanostructures is obtained showing geometrical shape- and size-dependent electronic screening in nanostructures that manifest important consequences in charge storage enhancement or reduction.
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Affiliation(s)
| | - Rama Kant
- Department of Chemistry, University of Delhi, Delhi 110 007, India
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46
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Abstract
A reply to the comment by A. Yu. Kuntsevich and V. M. Pudalov.
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Affiliation(s)
- R L J Qiu
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - X P A Gao
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA
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47
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Caprara S, Peronaci F, Grilli M. Intrinsic instability of electronic interfaces with strong Rashba coupling. PHYSICAL REVIEW LETTERS 2012; 109:196401. [PMID: 23215408 DOI: 10.1103/physrevlett.109.196401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Indexed: 06/01/2023]
Abstract
We consider a model for the two-dimensional electron gas formed at the interface of oxide heterostructures, which includes a Rashba spin-orbit coupling proportional to the electric field perpendicular to the interface. Based on the standard mechanism of polarity catastrophe, we assume that the electric field has a contribution proportional to the electron density. Under these simple and general assumptions, we show that a phase separation instability (signaled by a negative compressibility) occurs for realistic values of the spin-orbit coupling and of the electronic band-structure parameters. This provides an intrinsic mechanism for the inhomogeneous phases observed at the LaAlO(3)/SrTiO(3) or LaTiO(3)/SrTiO(3) interfaces.
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Affiliation(s)
- S Caprara
- Dipartimento di Fisica, Università di Roma La Sapienza, P Aldo Moro 5, 00185 Roma, Italy
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48
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Srisonphan S, Jung YS, Kim HK. Metal-oxide-semiconductor field-effect transistor with a vacuum channel. NATURE NANOTECHNOLOGY 2012; 7:504-8. [PMID: 22751220 DOI: 10.1038/nnano.2012.107] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 05/22/2012] [Indexed: 05/21/2023]
Abstract
High-speed electronic devices rely on short carrier transport times, which are usually achieved by decreasing the channel length and/or increasing the carrier velocity. Ideally, the carriers enter into a ballistic transport regime in which they are not scattered. However, it is difficult to achieve ballistic transport in a solid-state medium because the high electric fields used to increase the carrier velocity also increase scattering. Vacuum is an ideal medium for ballistic transport, but vacuum electronic devices commonly suffer from low emission currents and high operating voltages. Here, we report the fabrication of a low-voltage field-effect transistor with a vertical vacuum channel (channel length of ~20 nm) etched into a metal-oxide-semiconductor substrate. We measure a transconductance of 20 nS µm(-1), an on/off ratio of 500 and a turn-on gate voltage of 0.5 V under ambient conditions. Coulombic repulsion in the two-dimensional electron system at the interface between the oxide and the metal or the semiconductor reduces the energy barrier to electron emission, leading to a high emission current density (~1 × 10(5) A cm(-2)) under a bias of only 1 V. The emission of two-dimensional electron systems into vacuum channels could enable a new class of low-power, high-speed transistors.
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Affiliation(s)
- Siwapon Srisonphan
- Department of Electrical and Computer Engineering and Petersen Institute of NanoScience and Engineering, 1140 Benedum, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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49
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Kumar A, Arruda TM, Kim Y, Ivanov IN, Jesse S, Bark CW, Bristowe NC, Artacho E, Littlewood PB, Eom CB, Kalinin SV. Probing surface and bulk electrochemical processes on the LaAlO3-SrTiO3 interface. ACS NANO 2012; 6:3841-3852. [PMID: 22489563 DOI: 10.1021/nn204960c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Local electrochemical phenomena on the surfaces of the LaAlO(3)-SrTiO(3) heterostructure are explored using unipolar and bipolar dynamic electrochemical strain microscopy (D-ESM). The D-ESM suggests the presence of at least two distinct electrochemical processes, including fast reversible low-voltage process and slow high-voltage process. The latter process is associated with static surface deformations in the sub-nanometer regime. These behaviors are compared with Kelvin probe force microscopy hysteresis data. The possible origins of observed phenomena are discussed, and these studies suggest that charge-writing behavior in LAO-STO includes a strong surface/bulk electrochemical component and is more complicated than simple screening by surface adsorbates.
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Affiliation(s)
- Amit Kumar
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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50
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Au K, Li DF, Chan NY, Dai JY. Polar liquid molecule induced transport property modulation at LaAlO₃/SrTiO₃ heterointerface. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:2598-2602. [PMID: 22495936 DOI: 10.1002/adma.201200673] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Indexed: 05/31/2023]
Affiliation(s)
- K Au
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
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