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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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Gold C, Knothe A, Kurzmann A, Garcia-Ruiz A, Watanabe K, Taniguchi T, Fal'ko V, Ensslin K, Ihn T. Coherent Jetting from a Gate-Defined Channel in Bilayer Graphene. PHYSICAL REVIEW LETTERS 2021; 127:046801. [PMID: 34355933 DOI: 10.1103/physrevlett.127.046801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 05/18/2021] [Indexed: 06/13/2023]
Abstract
Graphene has evolved as a platform for quantum transport that can compete with the best and cleanest semiconductor systems. Here, we report on the observation of distinct electronic jets emanating from a narrow split-gate-defined channel in bilayer graphene. We find that these jets, which are visible via their interference patterns, occur predominantly with an angle of 60° between each other. This observation is related to the trigonal warping in the band structure of bilayer graphene, which, in conjunction with electron injection through a constriction, leads to a valley-dependent selection of momenta. This experimental observation of electron jetting has consequences for carrier transport in two-dimensional materials with a trigonally warped band structure in general, as well as for devices relying on ballistic and valley-selective transport.
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Affiliation(s)
- Carolin Gold
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Angelika Knothe
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Annika Kurzmann
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Aitor Garcia-Ruiz
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Vladimir Fal'ko
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
- Department of Physics, University of Manchester, Manchester M13 9PL, United Kingdom
- Henry Royce Institute, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Klaus Ensslin
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Thomas Ihn
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
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3
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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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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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Zhukov AA, Volk C, Winden A, Hardtdegen H, Schäpers T. Stability of charged density waves in InAs nanowires in an external magnetic field. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:475601. [PMID: 29094678 DOI: 10.1088/1361-648x/aa8d48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on magnetotransport measurements at [Formula: see text] K in a high-quality InAs nanowire ([Formula: see text] kΩ) in the presence of the charged tip of an atomic force microscope serving as a mobile gate. We demonstrate the crucial role of the external magnetic field on the amplitude of the charge density waves with a wavelength of 0.8 μm. The observed suppression rate of their amplitude is similar or slightly higher than the one for weak localization correction in our investigated InAs nanowire.
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Affiliation(s)
- A A Zhukov
- Institute of Solid State Physics, Russian Academy of Science, Chernogolovka, 142432, Russia
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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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Matsunaga M, Higuchi A, He G, Yamada T, Krüger P, Ochiai Y, Gong Y, Vajtai R, Ajayan PM, Bird JP, Aoki N. Nanoscale-Barrier Formation Induced by Low-Dose Electron-Beam Exposure in Ultrathin MoS 2 Transistors. ACS NANO 2016; 10:9730-9737. [PMID: 27704777 DOI: 10.1021/acsnano.6b05952] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Utilizing an innovative combination of scanning-probe and spectroscopic techniques, supported by first-principles calculations, we demonstrate how electron-beam exposure of field-effect transistors, implemented from ultrathin molybdenum disulfide (MoS2), may cause nanoscale structural modifications that in turn significantly modify the electrical operation of these devices. Quite surprisingly, these modifications are induced by even the relatively low electron doses used in conventional electron-beam lithography, which are found to induce compressive strain in the atomically thin MoS2. Likely arising from sulfur-vacancy formation in the exposed regions, the strain gives rise to a local widening of the MoS2 bandgap, an idea that is supported both by our experiment and by the results of first-principles calculations. A nanoscale potential barrier develops at the boundary between exposed and unexposed regions and may cause extrinsic variations in the resulting electrical characteristics exhibited by the transistor. The widespread use of electron-beam lithography in nanofabrication implies that the presence of such strain must be carefully considered when seeking to harness the potential of atomically thin transistors. At the same time, this work also promises the possibility of exploiting the strain as a means to achieve "bandstructure engineering" in such devices.
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Affiliation(s)
| | | | - Guanchen He
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | | | | | | | - Yongji Gong
- Department of Materials Science and Nano-Engineering, Rice University , Houston, Texas 77005, United States
| | - Robert Vajtai
- Department of Materials Science and Nano-Engineering, Rice University , Houston, Texas 77005, United States
| | - Pulickel M Ajayan
- Department of Materials Science and Nano-Engineering, Rice University , Houston, Texas 77005, United States
| | - Jonathan P Bird
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - Nobuyuki Aoki
- Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi 332-0012, Japan
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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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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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Kozikov AA, Steinacher R, Rössler C, Ihn T, Ensslin K, Reichl C, Wegscheider W. Mode Specific Backscattering in a Quantum Point Contact. NANO LETTERS 2015; 15:7994-7999. [PMID: 26569040 DOI: 10.1021/acs.nanolett.5b03170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate a scanning gate grid measurement technique consisting in measuring the conductance of a quantum point contact (QPC) as a function of gate voltage at each tip position. Unlike conventional scanning gate experiments, it allows investigating QPC conductance plateaus affected by the tip at these positions. We compensate the capacitive coupling of the tip to the QPC and discover that interference fringes coexist with distorted QPC plateaus. We spatially resolve the mode structure for each plateau.
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Affiliation(s)
- A A Kozikov
- Solid State Physics Laboratory, ETH Zürich , CH-8093 Zürich, Switzerland
| | - R Steinacher
- Solid State Physics Laboratory, ETH Zürich , CH-8093 Zürich, Switzerland
| | - C Rössler
- Solid State Physics Laboratory, ETH Zürich , CH-8093 Zürich, Switzerland
| | - T Ihn
- Solid State Physics Laboratory, ETH Zürich , CH-8093 Zürich, Switzerland
| | - K Ensslin
- Solid State Physics Laboratory, ETH Zürich , CH-8093 Zürich, Switzerland
| | - C Reichl
- Solid State Physics Laboratory, ETH Zürich , CH-8093 Zürich, Switzerland
| | - W Wegscheider
- Solid State Physics Laboratory, ETH Zürich , CH-8093 Zürich, Switzerland
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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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