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Pogosov AG, Shevyrin AA, Pokhabov DA, Zhdanov EY, Kumar S. Suspended semiconductor nanostructures: physics and technology. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:263001. [PMID: 35477698 DOI: 10.1088/1361-648x/ac6308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
The current state of research on quantum and ballistic electron transport in semiconductor nanostructures with a two-dimensional electron gas separated from the substrate and nanoelectromechanical systems is reviewed. These nanostructures fabricated using the surface nanomachining technique have certain unexpected features in comparison to their non-suspended counterparts, such as additional mechanical degrees of freedom, enhanced electron-electron interaction and weak heat sink. Moreover, their mechanical functionality can be used as an additional tool for studying the electron transport, complementary to the ordinary electrical measurements. The article includes a comprehensive review of spin-dependent electron transport and multichannel effects in suspended quantum point contacts, ballistic and adiabatic transport in suspended nanostructures, as well as investigations on nanoelectromechanical systems. We aim to provide an overview of the state-of-the-art in suspended semiconductor nanostructures and their applications in nanoelectronics, spintronics and emerging quantum technologies.
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Affiliation(s)
- A G Pogosov
- Rzhanov Institute of Semiconductor Physics SB RAS, 13 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Physics, Novosibirsk State University, 2 Pirogov Str., Novosibirsk 630090, Russia
| | - A A Shevyrin
- Rzhanov Institute of Semiconductor Physics SB RAS, 13 Lavrentiev Ave., Novosibirsk 630090, Russia
| | - D A Pokhabov
- Rzhanov Institute of Semiconductor Physics SB RAS, 13 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Physics, Novosibirsk State University, 2 Pirogov Str., Novosibirsk 630090, Russia
| | - E Yu Zhdanov
- Rzhanov Institute of Semiconductor Physics SB RAS, 13 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Physics, Novosibirsk State University, 2 Pirogov Str., Novosibirsk 630090, Russia
| | - S Kumar
- Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom
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2
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Kumar S, Pepper M. Interactions and non-magnetic fractional quantization in one-dimension. APPLIED PHYSICS LETTERS 2021; 119:110502. [PMID: 35382142 PMCID: PMC8970604 DOI: 10.1063/5.0061921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/27/2021] [Indexed: 06/14/2023]
Abstract
In this Perspective article, we present recent developments on interaction effects on the carrier transport properties of one-dimensional (1D) semiconductor quantum wires fabricated using the GaAs/AlGaAs system, particularly the emergence of the long predicted fractional quantization of conductance in the absence of a magnetic field. Over three decades ago, it was shown that transport through a 1D system leads to integer quantized conductance given by N·2e2/h, where N is the number of allowed energy levels (N = 1, 2, 3, …). Recent experiments have shown that a weaker confinement potential and low carrier concentration provide a testbed for electrons strongly interacting. The consequence leads to a reconfiguration of the electron distribution into a zigzag assembly which, unexpectedly, was found to exhibit quantization of conductance predominantly at 1/6, 2/5, 1/4, and 1/2 in units of e2/h. These fractional states may appear similar to the fractional states seen in the Fractional Quantum Hall Effect; however, the system does not possess a filling factor and they differ in the nature of their physical causes. The states may have promise for the emergent topological quantum computing schemes as they are controllable by gate voltages with a distinct identity.
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Affiliation(s)
- S. Kumar
- Author to whom correspondence should be addressed:
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3
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Hudson KL, Srinivasan A, Goulko O, Adam J, Wang Q, Yeoh LA, Klochan O, Farrer I, Ritchie DA, Ludwig A, Wieck AD, von Delft J, Hamilton AR. New signatures of the spin gap in quantum point contacts. Nat Commun 2021; 12:5. [PMID: 33397919 PMCID: PMC7782751 DOI: 10.1038/s41467-020-19895-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/12/2020] [Indexed: 11/09/2022] Open
Abstract
One dimensional semiconductor systems with strong spin-orbit interaction are both of fundamental interest and have potential applications to topological quantum computing. Applying a magnetic field can open a spin gap, a pre-requisite for Majorana zero modes. The spin gap is predicted to manifest as a field dependent dip on the first 1D conductance plateau. However, disorder and interaction effects make identifying spin gap signatures challenging. Here we study experimentally and numerically the 1D channel in a series of low disorder p-type GaAs quantum point contacts, where spin-orbit and hole-hole interactions are strong. We demonstrate an alternative signature for probing spin gaps, which is insensitive to disorder, based on the linear and non-linear response to the orientation of the applied magnetic field, and extract a spin-orbit gap ΔE ≈ 500 μeV. This approach could enable one-dimensional hole systems to be developed as a scalable and reproducible platform for topological quantum applications. In one-dimensional systems, the combination of a strong spin-orbit interaction and an applied magnetic field can give rise to a spin-gap, however experimental identification is difficult. Here, the authors present new signatures for the spin-gap, and verify these experimentally in hole QPCs.
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Affiliation(s)
- K L Hudson
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.,ARC Centre of Excellence in Future Low-Energy Electronics Technologies, University of New South Wales, Sydney, NSW, 2052, Australia
| | - A Srinivasan
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.,ARC Centre of Excellence in Future Low-Energy Electronics Technologies, University of New South Wales, Sydney, NSW, 2052, Australia
| | - O Goulko
- Department of Physics, University of Massachusetts, Boston, MA, 02125, USA
| | - J Adam
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Q Wang
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.,ARC Centre of Excellence in Future Low-Energy Electronics Technologies, University of New South Wales, Sydney, NSW, 2052, Australia
| | - L A Yeoh
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - O Klochan
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.,ARC Centre of Excellence in Future Low-Energy Electronics Technologies, University of New South Wales, Sydney, NSW, 2052, Australia
| | - I Farrer
- Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, UK
| | - D A Ritchie
- Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - A Ludwig
- Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - A D Wieck
- Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - J von Delft
- Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians Universität, München, Theresienstrasse 37, D-80333, München, Germany
| | - A R Hamilton
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia. .,ARC Centre of Excellence in Future Low-Energy Electronics Technologies, University of New South Wales, Sydney, NSW, 2052, Australia.
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4
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Abstract
Quantum point contacts (QPC) are a primary component in mesoscopic physics and have come to serve various purposes in modern quantum devices. However, fabricating a QPC that operates robustly under extreme conditions, such as high bias or magnetic fields, still remains an important challenge. As a solution, we have analyzed the trench-gated QPC (t-QPC) that has a central gate in addition to the split-gate structure used in conventional QPCs (c-QPC). From simulation and modelling, we predicted that the t-QPC has larger and more even subband spacings over a wider range of transmission when compared to the c-QPC. After an experimental verification, the two QPCs were investigated in the quantum Hall regimes as well. At high fields, the maximally available conductance was achievable in the t-QPC due to the local carrier density modulation by the trench gate. Furthermore, the t-QPC presented less anomalies in its DC bias dependence, indicating a possible suppression of impurity effects.
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Freudenfeld J, Geier M, Umansky V, Brouwer PW, Ludwig S. Coherent Electron Optics with Ballistically Coupled Quantum Point Contacts. PHYSICAL REVIEW LETTERS 2020; 125:107701. [PMID: 32955297 DOI: 10.1103/physrevlett.125.107701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 08/07/2020] [Indexed: 06/11/2023]
Abstract
The realization of integrated quantum circuits requires precise on-chip control of charge carriers. Aiming at the coherent coupling of distant nanostructures at zero magnetic field, here we study the ballistic electron transport through two quantum point contacts (QPCs) in series in a three terminal configuration. We enhance the coupling between the QPCs by electrostatic focusing using a field effect lens. To study the emission and collection properties of QPCs in detail we combine the electrostatic focusing with magnetic deflection. Comparing our measurements with quantum mechanical and classical calculations we discuss generic features of the quantum circuit and demonstrate how the coherent and ballistic dynamics depend on the details of the QPC confinement potentials.
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Affiliation(s)
- J Freudenfeld
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - M Geier
- Dahlem Center for Complex Quantum Systems and Physics Department, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - V Umansky
- Weizmann Institute of Science, Rehovot 76100, Israel
| | - P W Brouwer
- Dahlem Center for Complex Quantum Systems and Physics Department, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - S Ludwig
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, 10117 Berlin, Germany
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Rams MM, Zwolak M. Breaking the Entanglement Barrier: Tensor Network Simulation of Quantum Transport. PHYSICAL REVIEW LETTERS 2020; 124:137701. [PMID: 32302169 PMCID: PMC7654706 DOI: 10.1103/physrevlett.124.137701] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 10/08/2019] [Accepted: 02/21/2020] [Indexed: 06/11/2023]
Abstract
The recognition that large classes of quantum many-body systems have limited entanglement in the ground and low-lying excited states led to dramatic advances in their numerical simulation via so-called tensor networks. However, global dynamics elevates many particles into excited states, and can lead to macroscopic entanglement and the failure of tensor networks. Here, we show that for quantum transport-one of the most important cases of this failure-the fundamental issue is the canonical basis in which the scenario is cast: When particles flow through an interface, they scatter, generating a "bit" of entanglement between spatial regions with each event. The frequency basis naturally captures that-in the long-time limit and in the absence of inelastic scattering-particles tend to flow from a state with one frequency to a state of identical frequency. Recognizing this natural structure yields a striking-potentially exponential in some cases-increase in simulation efficiency, greatly extending the attainable spatial and time scales, and broadening the scope of tensor network simulation to hitherto inaccessible classes of nonequilibrium many-body problems.
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Affiliation(s)
- Marek M. Rams
- Jagiellonian University, Marian Smoluchowski Institute of Physics, Łojasiewicza 11, 30-348 Kraków, Poland
| | - Michael Zwolak
- Biophysics Group, Microsystems and Nanotechnology Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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Kohda M, Okayasu T, Nitta J. Spin-momentum locked spin manipulation in a two-dimensional Rashba system. Sci Rep 2019; 9:1909. [PMID: 30760759 PMCID: PMC6374388 DOI: 10.1038/s41598-018-37967-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/17/2018] [Indexed: 11/22/2022] Open
Abstract
Spin-momentum locking, which constrains spin orientation perpendicular to electron momentum, is attracting considerable interest for exploring various spin functionalities in semiconductors and topological materials. Efficient spin generation and spin detection have been demonstrated using the induced helical spin texture. Nevertheless, spin manipulation by spin-momentum locking remains a missing piece because, once bias voltage is applied to induce the current flow, the spin orientation must be locked by the electron momentum direction, thereby rendering spin phase control difficult. Herein, we demonstrate the spin-momentum locking-induced spin manipulation for ballistic electrons in a strong Rashba two-dimensional system. Electron spin rotates in a circular orbital motion for ballistically moving electrons, although spin orientation is locked towards the spin-orbit field because of the helical spin texture. This fact demonstrates spin manipulation by control of the electron orbital motion and reveals potential effects of the orbital degree of freedom on the spin phase for future spintronic and topological devices and for the processing of quantum information.
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Affiliation(s)
- Makoto Kohda
- Department of Materials Science, Tohoku University, 6-6-02 Aramaki-Aza Aoba, Aoba-ku, Sendai, 980-8579, Japan. .,Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan. .,Center for Science and Innovation in Spintronics (Core Research Cluster), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.
| | - Takanori Okayasu
- Department of Materials Science, Tohoku University, 6-6-02 Aramaki-Aza Aoba, Aoba-ku, Sendai, 980-8579, Japan
| | - Junsaku Nitta
- Department of Materials Science, Tohoku University, 6-6-02 Aramaki-Aza Aoba, Aoba-ku, Sendai, 980-8579, Japan.,Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.,Center for Science and Innovation in Spintronics (Core Research Cluster), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
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Mizokuchi R, Maurand R, Vigneau F, Myronov M, De Franceschi S. Ballistic One-Dimensional Holes with Strong g-Factor Anisotropy in Germanium. NANO LETTERS 2018; 18:4861-4865. [PMID: 29995419 DOI: 10.1021/acs.nanolett.8b01457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report experimental evidence of ballistic hole transport in one-dimensional quantum wires gate-defined in a strained SiGe/Ge/SiGe quantum well. At zero magnetic field, we observe conductance plateaus at integer multiples of 2 e2/ h. At finite magnetic field, the splitting of these plateaus by Zeeman effect reveals largely anisotropic g-factors with absolute values below 1 in the quantum-well plane, and exceeding 10 out-of-plane. This g-factor anisotropy is consistent with a heavy-hole character of the propagating valence-band states, which is in line with a predominant confinement in the growth direction. Remarkably, we observe quantized ballistic conductance in device channels up to 600 nm long. These findings mark an important step toward the realization of novel devices for applications in quantum spintronics.
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Affiliation(s)
- R Mizokuchi
- Université Grenoble Alpes & CEA, INAC-PHELIQS , F-38000 Grenoble , France
| | - R Maurand
- Université Grenoble Alpes & CEA, INAC-PHELIQS , F-38000 Grenoble , France
| | - F Vigneau
- Université Grenoble Alpes & CEA, INAC-PHELIQS , F-38000 Grenoble , France
| | - M Myronov
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - S De Franceschi
- Université Grenoble Alpes & CEA, INAC-PHELIQS , F-38000 Grenoble , France
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9
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Karlsson H, Yakimenko II, Berggren KF. Nature of magnetization and lateral spin-orbit interaction in gated semiconductor nanowires. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:215302. [PMID: 29623898 DOI: 10.1088/1361-648x/aabc15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Semiconductor nanowires are interesting candidates for realization of spintronics devices. In this paper we study electronic states and effects of lateral spin-orbit coupling (LSOC) in a one-dimensional asymmetrically biased nanowire using the Hartree-Fock method with Dirac interaction. We have shown that spin polarization can be triggered by LSOC at finite source-drain bias,as a result of numerical noise representing a random magnetic field due to wiring or a random background magnetic field by Earth magnetic field, for instance. The electrons spontaneously arrange into spin rows in the wire due to electron interactions leading to a finite spin polarization. The direction of polarization is, however, random at zero source-drain bias. We have found that LSOC has an effect on orientation of spin rows only in the case when source-drain bias is applied.
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10
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Edlbauer H, Takada S, Roussely G, Yamamoto M, Tarucha S, Ludwig A, Wieck AD, Meunier T, Bäuerle C. Non-universal transmission phase behaviour of a large quantum dot. Nat Commun 2017; 8:1710. [PMID: 29167429 PMCID: PMC5700201 DOI: 10.1038/s41467-017-01685-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 10/10/2017] [Indexed: 11/09/2022] Open
Abstract
The electron wave function experiences a phase modification at coherent transmission through a quantum dot. This transmission phase undergoes a characteristic shift of π when scanning through a Coulomb blockade resonance. Between successive resonances either a transmission phase lapse of π or a phase plateau is theoretically expected to occur depending on the parity of quantum dot states. Despite considerable experimental effort, this transmission phase behaviour has remained elusive for a large quantum dot. Here we report on transmission phase measurements across such a large quantum dot hosting hundreds of electrons. Scanning the transmission phase along 14 successive resonances with an original two-path interferometer, we observe both phase lapses and plateaus. We demonstrate that quantum dot deformation alters the sequence of phase lapses and plateaus via parity modifications of the involved quantum dot states. Our findings set a milestone towards an comprehensive understanding of the transmission phase of quantum dots.
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Affiliation(s)
- Hermann Edlbauer
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France
| | - Shintaro Takada
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France
- National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8563, Japan
| | - Grégoire Roussely
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France
| | - Michihisa Yamamoto
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 31-0198, Japan
| | - Seigo Tarucha
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 31-0198, Japan
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Tristan Meunier
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France
| | - Christopher Bäuerle
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France.
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11
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Schimmel DH, Bruognolo B, von Delft J. Spin Fluctuations in the 0.7 Anomaly in Quantum Point Contacts. PHYSICAL REVIEW LETTERS 2017; 119:196401. [PMID: 29219510 DOI: 10.1103/physrevlett.119.196401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Indexed: 06/07/2023]
Abstract
It has been argued that the 0.7 anomaly in quantum point contacts (QPCs) is due to an enhanced density of states at the top of the QPC barrier (the van Hove ridge), which strongly enhances the effects of interactions. Here, we analyze their effect on dynamical quantities. We find that they pin the van Hove ridge to the chemical potential when the QPC is subopen, cause a temperature dependence for the linear conductance that qualitatively agrees with experiments, strongly enhance the magnitude of the dynamical spin susceptibility, and significantly lengthen the QPC traversal time. We conclude that electrons traverse the QPC via a slowly fluctuating spin structure of finite spatial extent.
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Affiliation(s)
- Dennis H Schimmel
- Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany
| | - Benedikt Bruognolo
- Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - Jan von Delft
- Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany
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12
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Krinner S, Esslinger T, Brantut JP. Two-terminal transport measurements with cold atoms. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:343003. [PMID: 28749788 DOI: 10.1088/1361-648x/aa74a1] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In recent years, the ability of cold atom experiments to explore condensed-matter-related questions has dramatically progressed. Transport experiments, in particular, have expanded to the point in which conductance and other transport coefficients can now be measured in a way that is directly analogous to solid-state physics, extending cold-atom-based quantum simulations into the domain of quantum electronic devices. In this topical review, we describe the transport experiments performed with cold gases in the two-terminal configuration, with an emphasis on the specific features of cold atomic gases compared to solid-state physics. We present the experimental techniques and the main experimental findings, focusing on-but not restricted to-the recent experiments performed by our group. We finally discuss the perspectives opened up by this approach, the main technical and conceptual challenges for future developments, and potential applications in quantum simulation for transport phenomena and mesoscopic physics problems.
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Affiliation(s)
- Sebastian Krinner
- Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland
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13
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Abstract
We study particle and spin transport in a single-mode quantum point contact, using a charge neutral, quantum degenerate Fermi gas with tunable, attractive interactions. This yields the spin and particle conductance of the point contact as a function of chemical potential or confinement. The measurements cover a regime from weak attraction, where quantized conductance is observed, to the resonantly interacting superfluid. Spin conductance exhibits a broad maximum when varying the chemical potential at moderate interactions, which signals the emergence of Cooper pairing. In contrast, the particle conductance is unexpectedly enhanced even before the gas is expected to turn into a superfluid, continuously rising from the plateau at [Formula: see text] for weak interactions to plateau-like features at nonuniversal values as high as [Formula: see text] for intermediate interactions. For strong interactions, the particle conductance plateaus disappear and the spin conductance gets suppressed, confirming the spin-insulating character of a superfluid. Our observations document the breakdown of universal conductance quantization as many-body correlations appear. The observed anomalous quantization challenges a Fermi liquid description of the normal phase, shedding new light on the nature of the strongly attractive Fermi gas.
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14
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Kammhuber J, Cassidy MC, Zhang H, Gül Ö, Pei F, de Moor MWA, Nijholt B, Watanabe K, Taniguchi T, Car D, Plissard SR, Bakkers EPAM, Kouwenhoven LP. Conductance Quantization at Zero Magnetic Field in InSb Nanowires. NANO LETTERS 2016; 16:3482-3486. [PMID: 27121534 DOI: 10.1021/acs.nanolett.6b00051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ballistic electron transport is a key requirement for existence of a topological phase transition in proximitized InSb nanowires. However, measurements of quantized conductance as direct evidence of ballistic transport have so far been obscured due to the increased chance of backscattering in one-dimensional nanowires. We show that by improving the nanowire-metal interface as well as the dielectric environment we can consistently achieve conductance quantization at zero magnetic field. Additionally we study the contribution of orbital effects to the sub-band dispersion for different orientation of the magnetic field, observing a near-degeneracy between the second and third sub-bands.
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Affiliation(s)
- Jakob Kammhuber
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Maja C Cassidy
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Hao Zhang
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Önder Gül
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Fei Pei
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Michiel W A de Moor
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Bas Nijholt
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Kenji Watanabe
- Advanced Materials Laboratory, National Institute for Materials Science , 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Advanced Materials Laboratory, National Institute for Materials Science , 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Diana Car
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Sébastien R Plissard
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Erik P A M Bakkers
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Leo P Kouwenhoven
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
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15
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Heedt S, Prost W, Schubert J, Grützmacher D, Schäpers T. Ballistic Transport and Exchange Interaction in InAs Nanowire Quantum Point Contacts. NANO LETTERS 2016; 16:3116-3123. [PMID: 27104768 DOI: 10.1021/acs.nanolett.6b00414] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
One-dimensional ballistic transport is demonstrated for a high-mobility InAs nanowire device. Unlike conventional quantum point contacts (QPCs) created in a two-dimensional electron gas, the nanowire QPCs represent one-dimensional constrictions formed inside a quasi-one-dimensional conductor. For each QPC, the local subband occupation can be controlled individually between zero and up to six degenerate modes. At large out-of-plane magnetic fields Landau quantization and Zeeman splitting emerge and comprehensive voltage bias spectroscopy is performed. Confinement-induced quenching of the orbital motion gives rise to significantly modified subband-dependent Landé g factors. A pronounced g factor enhancement related to Coulomb exchange interaction is reported. Many-body effects of that kind also manifest in the observation of the 0.7·2e(2)/h conductance anomaly, commonly found in planar devices.
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Affiliation(s)
- S Heedt
- Peter Grünberg Institut (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich , 52425 Jülich, Germany
| | - W Prost
- Solid State Electronics Department, University of Duisburg-Essen , 47057 Duisburg, Germany
| | - J Schubert
- Peter Grünberg Institut (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich , 52425 Jülich, Germany
| | - D Grützmacher
- Peter Grünberg Institut (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich , 52425 Jülich, Germany
| | - Th Schäpers
- Peter Grünberg Institut (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich , 52425 Jülich, Germany
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16
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Brun B, Martins F, Faniel S, Hackens B, Cavanna A, Ulysse C, Ouerghi A, Gennser U, Mailly D, Simon P, Huant S, Bayot V, Sanquer M, Sellier H. Electron Phase Shift at the Zero-Bias Anomaly of Quantum Point Contacts. PHYSICAL REVIEW LETTERS 2016; 116:136801. [PMID: 27081995 DOI: 10.1103/physrevlett.116.136801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Indexed: 06/05/2023]
Abstract
The Kondo effect is the many-body screening of a local spin by a cloud of electrons at very low temperature. It has been proposed as an explanation of the zero-bias anomaly in quantum point contacts where interactions drive a spontaneous charge localization. However, the Kondo origin of this anomaly remains under debate, and additional experimental evidence is necessary. Here we report on the first phase-sensitive measurement of the zero-bias anomaly in quantum point contacts using a scanning gate microscope to create an electronic interferometer. We observe an abrupt shift of the interference fringes by half a period in the bias range of the zero-bias anomaly, a behavior which cannot be reproduced by single-particle models. We instead relate it to the phase shift experienced by electrons scattering off a Kondo system. Our experiment therefore provides new evidence of this many-body effect in quantum point contacts.
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Affiliation(s)
- B Brun
- Université Grenoble Alpes, F-38000 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
| | - F Martins
- IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - S Faniel
- IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - B Hackens
- IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - A Cavanna
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - C Ulysse
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - A Ouerghi
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - U Gennser
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - D Mailly
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - P Simon
- Laboratoire de Physique des Solides, Université Paris-Sud, F-91405 Orsay, France
| | - S Huant
- Université Grenoble Alpes, F-38000 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
| | - V Bayot
- Université Grenoble Alpes, F-38000 Grenoble, France
- IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - M Sanquer
- Université Grenoble Alpes, F-38000 Grenoble, France
- CEA, INAC-SPSMS, F-38054 Grenoble, France
| | - H Sellier
- Université Grenoble Alpes, F-38000 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
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17
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Vionnet G, Sushkov OP. Enhancement Mechanism of the Electron g Factor in Quantum Point Contacts. PHYSICAL REVIEW LETTERS 2016; 116:126801. [PMID: 27058089 DOI: 10.1103/physrevlett.116.126801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Indexed: 06/05/2023]
Abstract
The electron g factor measured in a quantum point contact by source-drain bias spectroscopy is significantly larger than its value in a two-dimensional electron gas. This enhancement, established experimentally in numerous studies, is an outstanding puzzle. In the present work we explain the mechanism of this enhancement in a theory accounting for the electron-electron interactions. We show that the effect relies crucially on the nonequilibrium nature of the spectroscopy at finite bias.
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Affiliation(s)
- Grégoire Vionnet
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia and Institute of Theoretical Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Oleg P Sushkov
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
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18
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Yakimenko II, Berggren KF. Probing dopants in wide semiconductor quantum point contacts. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:105801. [PMID: 26885626 DOI: 10.1088/0953-8984/28/10/105801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Effects of randomly distributed impurities on conductance, spin polarization and electron localization in realistic gated semiconductor quantum point contacts (QPCs) have been simulated numerically. To this end density functional theory in the local spin-density approximation has been used. In the case when the donor layer is embedded far from the two-dimensional electron gas (2DEG) the electrostatic confinement potential exhibits the conventional parabolic form, and thus the usual ballistic transport phenomena take place both in the devices with split gates alone and with an additional metallic gate on the top. In the opposite case, i.e. when the randomly distributed donors are placed not far away from the 2DEG layer, there are drastic changes like the localization of electrons in the vicinity of confinement potential minima which give rise to fluctuations in conductance and resonances. The conductance as a function of the voltage applied to the top gate for asymmetrically charged split gates has been calculated. In this case resonances in conductance caused by randomly distributed donors are shifted and decrease in amplitude while the anomalies caused by interaction effects remain unmodified. It has been also shown that for a wide QPC the polarization can appear in the form of stripes. The importance of partial ionization of the random donors and the possibility of short range order among the ionized donors are emphasized. The motivation for this work is to critically evaluate the nature of impurities and how to guide the design of high-mobility devices.
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Affiliation(s)
- I I Yakimenko
- Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping, Sweden
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19
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Farghadan R, Sehat A. Enhancement of Rashba spin–orbit coupling by electron–electron interaction. RSC Adv 2016. [DOI: 10.1039/c6ra16289d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We studied how the electron–electron interaction enhances the strength of the Rashba spin–orbit coupling and opens the possibility of generating a spin-polarized output current from an unpolarized electric current without any magnetic elements.
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Affiliation(s)
| | - Ali Sehat
- Department of Physics
- University of Kashan
- Kashan
- Iran
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20
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Kawamura M, Ono K, Stano P, Kono K, Aono T. Electronic Magnetization of a Quantum Point Contact Measured by Nuclear Magnetic Resonance. PHYSICAL REVIEW LETTERS 2015; 115:036601. [PMID: 26230812 DOI: 10.1103/physrevlett.115.036601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Indexed: 06/04/2023]
Abstract
We report an electronic magnetization measurement of a quantum point contact (QPC) based on nuclear magnetic resonance (NMR) spectroscopy. We find that NMR signals can be detected by measuring the QPC conductance under in-plane magnetic fields. This makes it possible to measure, from Knight shifts of the NMR spectra, the electronic magnetization of a QPC containing only a few electron spins. The magnetization changes smoothly with the QPC potential barrier height and peaks at the conductance plateau of 0.5×2e^{2}/h. The observed features are well captured by a model calculation assuming a smooth potential barrier, supporting a no bound state origin of the 0.7 structure.
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Affiliation(s)
- Minoru Kawamura
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
| | - Keiji Ono
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
| | - Peter Stano
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
- Institute of Physics, Slovak Academy of Sciences, 84511 Bratislava, Slovakia
| | - Kimitoshi Kono
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
| | - Tomosuke Aono
- Department of Electrical and Electronic Engineering, Ibaraki University, Hitachi 316-8511, Japan
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21
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Chen CC, Chang YC, Kuo DMT. Quantum interference and electron correlation in charge transport through triangular quantum dot molecules. Phys Chem Chem Phys 2015; 17:6606-11. [PMID: 25660124 DOI: 10.1039/c5cp00053j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the charge transport properties of triangular quantum dot molecules (TQDMs) connected to metallic electrodes, taking into account all correlation functions and relevant charging states. The quantum interference (QI) effect of TQDMs resulting from electron coherent tunneling between quantum dots is revealed and well interpreted by the long distance coherent tunneling mechanism. The spectra of electrical conductance of TQDMs with charge filling from one to six electrons clearly depict the many-body and topological effects. The calculated charge stability diagram for conductance and total occupation numbers matches well with the recent experimental measurements. We also demonstrate that the destructive QI effect on the tunneling current of TQDMs is robust with respect to temperature variation, making the single electron QI transistor feasible at higher temperatures.
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Affiliation(s)
- Chih-Chieh Chen
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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22
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Chuang P, Ho SC, Smith LW, Sfigakis F, Pepper M, Chen CH, Fan JC, Griffiths JP, Farrer I, Beere HE, Jones GAC, Ritchie DA, Chen TM. All-electric all-semiconductor spin field-effect transistors. NATURE NANOTECHNOLOGY 2015; 10:35-39. [PMID: 25531088 DOI: 10.1038/nnano.2014.296] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 11/11/2014] [Indexed: 06/04/2023]
Abstract
The spin field-effect transistor envisioned by Datta and Das opens a gateway to spin information processing. Although the coherent manipulation of electron spins in semiconductors is now possible, the realization of a functional spin field-effect transistor for information processing has yet to be achieved, owing to several fundamental challenges such as the low spin-injection efficiency due to resistance mismatch, spin relaxation and the spread of spin precession angles. Alternative spin transistor designs have therefore been proposed, but these differ from the field-effect transistor concept and require the use of optical or magnetic elements, which pose difficulties for incorporation into integrated circuits. Here, we present an all-electric and all-semiconductor spin field-effect transistor in which these obstacles are overcome by using two quantum point contacts as spin injectors and detectors. Distinct engineering architectures of spin-orbit coupling are exploited for the quantum point contacts and the central semiconductor channel to achieve complete control of the electron spins (spin injection, manipulation and detection) in a purely electrical manner. Such a device is compatible with large-scale integration and holds promise for future spintronic devices for information processing.
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Affiliation(s)
- Pojen Chuang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Sheng-Chin Ho
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - L W Smith
- Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - F Sfigakis
- Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - M Pepper
- Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK
| | - Chin-Hung Chen
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Ju-Chun Fan
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - J P Griffiths
- Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - I Farrer
- Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - H E Beere
- Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - G A C Jones
- Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - D A Ritchie
- Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Tse-Ming Chen
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
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23
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Goulko O, Bauer F, Heyder J, von Delft J. Effect of spin-orbit interactions on the 0.7 anomaly in quantum point contacts. PHYSICAL REVIEW LETTERS 2014; 113:266402. [PMID: 25615360 DOI: 10.1103/physrevlett.113.266402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Indexed: 06/04/2023]
Abstract
We study how the conductance of a quantum point contact is affected by spin-orbit interactions, for systems at zero temperature both with and without electron-electron interactions. In the presence of spin-orbit coupling, tuning the strength and direction of an external magnetic field can change the dispersion relation and hence the local density of states in the point contact region. This modifies the effect of electron-electron interactions, implying striking changes in the shape of the 0.7-anomaly and introducing additional distinctive features in the first conductance step.
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Affiliation(s)
- Olga Goulko
- Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany and Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Florian Bauer
- Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany
| | - Jan Heyder
- Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany
| | - Jan von Delft
- Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany
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24
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Wigner and Kondo physics in quantum point contacts revealed by scanning gate microscopy. Nat Commun 2014; 5:4290. [DOI: 10.1038/ncomms5290] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 06/04/2014] [Indexed: 11/09/2022] Open
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25
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Xiang S, Xiao S, Fuji K, Shibuya K, Endo T, Yumoto N, Morimoto T, Aoki N, Bird JP, Ochiai Y. On the zero-bias anomaly and Kondo physics in quantum point contacts near pinch-off. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:125304. [PMID: 24599094 DOI: 10.1088/0953-8984/26/12/125304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We investigate the linear and non-linear conductance of quantum point contacts (QPCs), in the region near pinch-off where Kondo physics has previously been connected to the appearance of the 0.7 feature. In studies of seven different QPCs, fabricated in the same high-mobility GaAs/AlGaAs heterojunction, the linear conductance is widely found to show the presence of the 0.7 feature. The differential conductance, on the other hand, does not generally exhibit the zero-bias anomaly (ZBA) that has been proposed to indicate the Kondo effect. Indeed, even in the small subset of QPCs found to exhibit such an anomaly, the linear conductance does not always follow the universal temperature-dependent scaling behavior expected for the Kondo effect. Taken collectively, our observations demonstrate that, unlike the 0.7 feature, the ZBA is not a generic feature of low-temperature QPC conduction. We furthermore conclude that the mere observation of the ZBA alone is insufficient evidence for concluding that Kondo physics is active. While we do not rule out the possibility that the Kondo effect may occur in QPCs, our results appear to indicate that its observation requires a very strict set of conditions to be satisfied. This should be contrasted with the case of the 0.7 feature, which has been apparent since the earliest experimental investigations of QPC transport.
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Affiliation(s)
- S Xiang
- Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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26
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Khatua P, Bansal B, Shahar D. Single-slit electron diffraction with Aharonov-Bohm phase: Feynman's thought experiment with quantum point contacts. PHYSICAL REVIEW LETTERS 2014; 112:010403. [PMID: 24483873 DOI: 10.1103/physrevlett.112.010403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Indexed: 06/03/2023]
Abstract
In a "thought experiment," now a classic in physics pedagogy, Feynman visualizes Young's double-slit interference experiment with electrons in magnetic field. He shows that the addition of an Aharonov-Bohm phase is equivalent to shifting the zero-field wave interference pattern by an angle expected from the Lorentz force calculation for classical particles. We have performed this experiment with one slit, instead of two, where ballistic electrons within two-dimensional electron gas diffract through a small orifice formed by a quantum point contact (QPC). As the QPC width is comparable to the electron wavelength, the observed intensity profile is further modulated by the transverse waveguide modes present at the injector QPC. Our experiments open the way to realizing diffraction-based ideas in mesoscopic physics.
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Affiliation(s)
- Pradip Khatua
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel and Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Nadia 741252, West Bengal, India
| | - Bhavtosh Bansal
- Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Nadia 741252, West Bengal, India
| | - Dan Shahar
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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