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Michailow W, Spencer P, Almond NW, Kindness SJ, Wallis R, Mitchell TA, Degl’Innocenti R, Mikhailov SA, Beere HE, Ritchie DA. An in-plane photoelectric effect in two-dimensional electron systems for terahertz detection. SCIENCE ADVANCES 2022; 8:eabi8398. [PMID: 35427162 PMCID: PMC9012455 DOI: 10.1126/sciadv.abi8398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
Many mid- and far-infrared semiconductor photodetectors rely on a photonic response, when the photon energy is large enough to excite and extract electrons due to optical transitions. Toward the terahertz range with photon energies of a few milli-electron volts, classical mechanisms are used instead. This is the case in two-dimensional electron systems, where terahertz detection is dominated by plasmonic mixing and by scattering-based thermal phenomena. Here, we report on the observation of a quantum, collision-free phenomenon that yields a giant photoresponse at terahertz frequencies (1.9 THz), more than 10-fold as large as expected from plasmonic mixing. We artificially create an electrically tunable potential step within a degenerate two-dimensional electron gas. When exposed to terahertz radiation, electrons absorb photons and generate a large photocurrent under zero source-drain bias. The observed phenomenon, which we call the "in-plane photoelectric effect," provides an opportunity for efficient direct detection across the entire terahertz range.
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Affiliation(s)
- Wladislaw Michailow
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Peter Spencer
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Nikita W. Almond
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Stephen J. Kindness
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Robert Wallis
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Thomas A. Mitchell
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | | | | | - Harvey E. Beere
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - David A. Ritchie
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
- Swansea University, Singleton Park, Sketty, Swansea SA2 8PP, UK
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2
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Strunk C. Quantum Transport of Particles and Entropy. ENTROPY 2021; 23:e23121573. [PMID: 34945879 PMCID: PMC8700429 DOI: 10.3390/e23121573] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/04/2021] [Accepted: 11/09/2021] [Indexed: 11/16/2022]
Abstract
A unified view on macroscopic thermodynamics and quantum transport is presented. Thermodynamic processes with an exchange of energy between two systems necessarily involve the flow of other balancable quantities. These flows are first analyzed using a simple drift-diffusion model, which includes the thermoelectric effects, and connects the various transport coefficients to certain thermodynamic susceptibilities and a diffusion coefficient. In the second part of the paper, the connection between macroscopic thermodynamics and quantum statistics is discussed. It is proposed to employ not particles, but elementary Fermi- or Bose-systems as the elementary building blocks of ideal quantum gases. In this way, the transport not only of particles but also of entropy can be derived in a concise way, and is illustrated both for ballistic quantum wires, and for diffusive conductors. In particular, the quantum interference of entropy flow is in close correspondence to that of electric current.
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Affiliation(s)
- Christoph Strunk
- Institute of Experimental and Applied Physics, University of Regensburg, D-93025 Regensburg, Germany
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3
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Müller VL, Yan Y, Kashuba O, Trauzettel B, Abdelghany M, Kleinlein J, Beugeling W, Buhmann H, Molenkamp LW. Electron-Hole Scattering Limited Transport of Dirac Fermions in a Topological Insulator. NANO LETTERS 2021; 21:5195-5200. [PMID: 34115500 DOI: 10.1021/acs.nanolett.1c01271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We have experimentally investigated the effect of electron temperature on transport in the two-dimensional Dirac surface states of the three-dimensional topological insulator HgTe. We have found that around the minimal conductivity point, where both electrons and holes are present, heating the carriers with a DC current results in a nonmonotonic differential resistance of narrow channels. We have shown that the observed initial increase in resistance can be attributed to electron-hole scattering, while the decrease follows naturally from the change in Fermi energy of the charge carriers. Both effects are governed dominantly by a van Hove singularity in the bulk valence band. The results demonstrate the importance of interband electron-hole scattering in the transport properties of topological insulators.
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Affiliation(s)
- Valentin L Müller
- Institute for Topological Insulators and Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Yuan Yan
- Institute for Topological Insulators and Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Oleksiy Kashuba
- Theoretische Physik IV, Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany
| | - Björn Trauzettel
- Theoretische Physik IV, Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany
| | - Mohamed Abdelghany
- Institute for Topological Insulators and Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Johannes Kleinlein
- Institute for Topological Insulators and Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Wouter Beugeling
- Institute for Topological Insulators and Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Hartmut Buhmann
- Institute for Topological Insulators and Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Laurens W Molenkamp
- Institute for Topological Insulators and Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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4
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Fust S, Faustmann A, Carrad DJ, Bissinger J, Loitsch B, Döblinger M, Becker J, Abstreiter G, Finley JJ, Koblmüller G. Quantum-Confinement-Enhanced Thermoelectric Properties in Modulation-Doped GaAs-AlGaAs Core-Shell Nanowires. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1905458. [PMID: 31814176 DOI: 10.1002/adma.201905458] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 11/19/2019] [Indexed: 06/10/2023]
Abstract
Nanowires (NWs) hold great potential in advanced thermoelectrics due to their reduced dimensions and low-dimensional electronic character. However, unfavorable links between electrical and thermal conductivity in state-of-the-art unpassivated NWs have, so far, prevented the full exploitation of their distinct advantages. A promising model system for a surface-passivated one-dimensional (1D)-quantum confined NW thermoelectric is developed that enables simultaneously the observation of enhanced thermopower via quantum oscillations in the thermoelectric transport and a strong reduction in thermal conductivity induced by the core-shell heterostructure. High-mobility modulation-doped GaAs/AlGaAs core-shell NWs with thin (sub-40 nm) GaAs NW core channel are employed, where the electrical and thermoelectric transport is characterized on the same exact 1D-channel. 1D-sub-band transport at low temperature is verified by a discrete stepwise increase in the conductance, which coincided with strong oscillations in the corresponding Seebeck voltage that decay with increasing sub-band number. Peak Seebeck coefficients as high as ≈65-85 µV K-1 are observed for the lowest sub-bands, resulting in equivalent thermopower of S2 σ ≈ 60 µW m-1 K-2 and S2 G ≈ 0.06 pW K-2 within a single sub-band. Remarkably, these core-shell NW heterostructures also exhibit thermal conductivities as low as ≈3 W m-1 K-1 , about one order of magnitude lower than state-of-the-art unpassivated GaAs NWs.
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Affiliation(s)
- Sergej Fust
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
| | - Anton Faustmann
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
| | - Damon J Carrad
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
| | - Jochen Bissinger
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
| | - Bernhard Loitsch
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
| | - Markus Döblinger
- Department of Chemistry, Ludwig-Maximilians-University Munich, Butenandtstr. 11, 81377, Munich, Germany
| | - Jonathan Becker
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
| | - Gerhard Abstreiter
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
| | - Jonathan J Finley
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
| | - Gregor Koblmüller
- Walter Schottky Institut and Physik Department, Technical University of Munich, Am Coulombwall 4, 85748, Garching, Germany
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5
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How to measure the entropy of a mesoscopic system via thermoelectric transport. Nat Commun 2019; 10:5801. [PMID: 31862879 PMCID: PMC6925120 DOI: 10.1038/s41467-019-13630-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 11/12/2019] [Indexed: 11/08/2022] Open
Abstract
Entropy is a fundamental thermodynamic quantity indicative of the accessible degrees of freedom in a system. While it has been suggested that the entropy of a mesoscopic system can yield nontrivial information on emergence of exotic states, its measurement in such small electron-number system is a daunting task. Here we propose a method to extract the entropy of a Coulomb-blockaded mesoscopic system from transport measurements. We prove analytically and demonstrate numerically the applicability of the method to such a mesoscopic system of arbitrary spectrum and degeneracies. We then apply our procedure to measurements of thermoelectric response of a single quantum dot, and demonstrate how it can be used to deduce the entropy change across Coulomb-blockade valleys, resolving, along the way, a long-standing puzzle of the experimentally observed finite thermoelectric response at the apparent particle-hole symmetric point.
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6
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Sierra MA, López R, Lim JS. Thermally Driven Out-of-Equilibrium Two-Impurity Kondo System. PHYSICAL REVIEW LETTERS 2018; 121:096801. [PMID: 30230870 DOI: 10.1103/physrevlett.121.096801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Indexed: 06/08/2023]
Abstract
The archetypal two-impurity Kondo problem in a serially coupled double quantum dot is investigated in the presence of a thermal bias θ. The slave-boson formulation is employed to obtain the nonlinear thermal and thermoelectrical responses. When the Kondo correlations prevail over the antiferromagnetic coupling J between dot spins, we demonstrate that the setup shows negative differential thermal conductance regions behaving as a thermal diode. In addition, we report a sign reversal of the thermoelectric current I(θ) controlled by t/Γ (t and Γ denote the interdot tunnel and reservoir-dot tunnel couplings, respectively) and θ. All these features are attributed to the fact that at large θ both Q(θ) (heat current) and I(θ) are suppressed regardless of the value of t/Γ because the double dot decouples at high thermal biases. Finally, for a finite J, we investigate how the Kondo-to-antiferromagnetic crossover is altered by θ.
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Affiliation(s)
- Miguel A Sierra
- Institut de Física Interdisciplinària i de Sistemes Complexos IFISC (CSIC-UIB), E-07122 Palma de Mallorca, Spain
| | - Rosa López
- Institut de Física Interdisciplinària i de Sistemes Complexos IFISC (CSIC-UIB), E-07122 Palma de Mallorca, Spain
| | - Jong Soo Lim
- School of Physics, Korea Institute for Advanced Study, Seoul 130-722, Korea
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7
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Samuelsson P, Kheradsoud S, Sothmann B. Optimal Quantum Interference Thermoelectric Heat Engine with Edge States. PHYSICAL REVIEW LETTERS 2017; 118:256801. [PMID: 28696742 DOI: 10.1103/physrevlett.118.256801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Indexed: 06/07/2023]
Abstract
We show theoretically that a thermoelectric heat engine, operating exclusively due to quantum-mechanical interference, can reach optimal linear-response performance. A chiral edge state implementation of a close-to-optimal heat engine is proposed in an electronic Mach-Zehnder interferometer with a mesoscopic capacitor coupled to one arm. We demonstrate that the maximum power and corresponding efficiency can reach 90% and 83%, respectively, of the theoretical maximum. The proposed heat engine can be realized with existing experimental techniques and has a performance robust against moderate dephasing.
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Affiliation(s)
- Peter Samuelsson
- Physics Department and NanoLund, Lund University, Box 118, SE-22100 Lund, Sweden
| | - Sara Kheradsoud
- Physics Department and NanoLund, Lund University, Box 118, SE-22100 Lund, Sweden
| | - Björn Sothmann
- Theoretische Physik, Universität Duisburg-Essen and CENIDE, D-47048 Duisburg, Germany
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8
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Thierschmann H, Sánchez R, Sothmann B, Arnold F, Heyn C, Hansen W, Buhmann H, Molenkamp LW. Three-terminal energy harvester with coupled quantum dots. NATURE NANOTECHNOLOGY 2015; 10:854-8. [PMID: 26280407 DOI: 10.1038/nnano.2015.176] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 07/08/2015] [Indexed: 05/11/2023]
Abstract
Rectification of thermal fluctuations in mesoscopic conductors is the key idea behind recent attempts to build nanoscale thermoelectric energy harvesters to convert heat into useful electric power. So far, most concepts have made use of the Seebeck effect in a two-terminal geometry, where heat and charge are both carried by the same particles. Here, we experimentally demonstrate the working principle of a new kind of energy harvester, proposed recently, using two capacitively coupled quantum dots. We show that, due to the novel three-terminal design of our device, which spatially separates the heat reservoir from the conductor circuit, the directions of charge and heat flow become decoupled. This enables us to manipulate the direction of the generated charge current by means of external gate voltages while leaving the direction of heat flow unaffected. Our results pave the way for a new generation of multi-terminal nanoscale heat engines.
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Affiliation(s)
- Holger Thierschmann
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany
| | - Rafael Sánchez
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, Madrid 28049, Spain
| | - Björn Sothmann
- Département de Physique Théorique, Université de Genève, Genève 4 CH-1211, Switzerland
| | - Fabian Arnold
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany
| | - Christian Heyn
- Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, Hamburg D-20355, Germany
| | - Wolfgang Hansen
- Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, Hamburg D-20355, Germany
| | - Hartmut Buhmann
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany
| | - Laurens W Molenkamp
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany
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9
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Sánchez R, Sothmann B, Jordan AN. Chiral thermoelectrics with quantum Hall edge states. PHYSICAL REVIEW LETTERS 2015; 114:146801. [PMID: 25910147 DOI: 10.1103/physrevlett.114.146801] [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] [Indexed: 06/04/2023]
Abstract
The thermoelectric properties of a three-terminal quantum Hall conductor are investigated. We identify a contribution to the thermoelectric response that relies on the chirality of the carrier motion rather than on spatial asymmetries. The Onsager matrix becomes maximally asymmetric with configurations where either the Seebeck or the Peltier coefficients are zero while the other one remains finite. Reversing the magnetic field direction exchanges these effects, which originate from the chiral nature of the quantum Hall edge states. The possibility to generate spin-polarized currents in quantum spin Hall samples is discussed.
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Affiliation(s)
- Rafael Sánchez
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
| | - Björn Sothmann
- Département de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland
| | - Andrew N Jordan
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
- Institute for Quantum Studies, Chapman University, Orange, California 92866, USA
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10
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Sothmann B, Sánchez R, Jordan AN. Thermoelectric energy harvesting with quantum dots. NANOTECHNOLOGY 2015; 26:032001. [PMID: 25549281 DOI: 10.1088/0957-4484/26/3/032001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We review recent theoretical work on thermoelectric energy harvesting in multi-terminal quantum-dot setups. We first discuss several examples of nanoscale heat engines based on Coulomb-coupled conductors. In particular, we focus on quantum dots in the Coulomb-blockade regime, chaotic cavities and resonant tunneling through quantum dots and wells. We then turn toward quantum-dot heat engines that are driven by bosonic degrees of freedom such as phonons, magnons and microwave photons. These systems provide interesting connections to spin caloritronics and circuit quantum electrodynamics.
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Affiliation(s)
- Björn Sothmann
- Département de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland
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11
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Jezouin S, Parmentier FD, Anthore A, Gennser U, Cavanna A, Jin Y, Pierre F. Quantum Limit of Heat Flow Across a Single Electronic Channel. Science 2013; 342:601-4. [DOI: 10.1126/science.1241912] [Citation(s) in RCA: 189] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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12
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Pei W, Xie XC, Sun QF. Transient heat generation in a quantum dot under a step-like pulse bias. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:415302. [PMID: 23014101 DOI: 10.1088/0953-8984/24/41/415302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We study the transient heat generation in a quantum dot system driven by a step-like or a square-shaped pulse bias. We find that a periodically oscillating heat generation arises after adding the sudden bias. One particularly surprising result is that there exists a heat absorption from the zero-temperature phonon subsystem. Thus the phonon population in non-equilibrium can be less than that of the equilibrium electron-phonon system. In addition, we also ascertain the optimal conditions for the operation of a quantum dot with the minimum heat generation.
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Affiliation(s)
- Wei Pei
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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13
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Micolich AP. What lurks below the last plateau: experimental studies of the 0.7 × 2e(2)/h conductance anomaly in one-dimensional systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:443201. [PMID: 21997403 DOI: 10.1088/0953-8984/23/44/443201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The integer quantised conductance of one-dimensional electron systems is a well-understood effect of quantum confinement. A number of fractionally quantised plateaus are also commonly observed. They are attributed to many-body effects, but their precise origin is still a matter of debate, having attracted considerable interest over the past 15 years. This review reports on experimental studies of fractionally quantised plateaus in semiconductor quantum point contacts and quantum wires, focusing on the 0.7 × 2e(2)/h conductance anomaly, its analogues at higher conductances and the zero-bias peak observed in the dc source-drain bias for conductances less than 2e(2)/h.
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Affiliation(s)
- A P Micolich
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
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14
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Naydenova T, Dürrenfeld P, Tavakoli K, Pégard N, Ebel L, Pappert K, Brunner K, Gould C, Molenkamp LW. Diffusion thermopower of (Ga,Mn)As/GaAs tunnel junctions. PHYSICAL REVIEW LETTERS 2011; 107:197201. [PMID: 22181638 DOI: 10.1103/physrevlett.107.197201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Indexed: 05/31/2023]
Abstract
We report the observation of tunneling anisotropic magnetothermopower, a voltage response to a temperature difference across an interface between a normal and a magnetic semiconductor. The resulting voltage is related to the energy derivative of the density of states in the magnetic material, and thus has a strongly anisotropic response to the direction of magnetization in the material. The effect will have relevance to the operation of semiconductor spintronic devices, and may indeed already play a role in correctly interpreting the details of some earlier spin injection studies.
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Affiliation(s)
- Ts Naydenova
- Physikalisches Institut EP3, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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15
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Smith LW, Hamilton AR, Thomas KJ, Pepper M, Farrer I, Griffiths JP, Jones GAC, Ritchie DA. Compressibility measurements of quasi-one-dimensional quantum wires. PHYSICAL REVIEW LETTERS 2011; 107:126801. [PMID: 22026783 DOI: 10.1103/physrevlett.107.126801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Indexed: 05/31/2023]
Abstract
We report measurements of the compressibility of a one-dimensional quantum wire, defined in the upper well of a GaAs/AlGaAs double quantum well heterostructure. A wire defined simultaneously in the lower well probes the ability of the upper wire to screen the electric field from a biased surface gate. The technique is sensitive enough to resolve spin splitting of the subbands in the presence of an in-plane magnetic field. We measure a compressibility signal due to the 0.7 structure and study its evolution with increasing temperature and magnetic field. We see no evidence of the formation of the quasibound state predicted by the Kondo model, instead our data are consistent with theories which predict that the 0.7 structure arises as a result of spontaneous spin polarization.
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Affiliation(s)
- L W Smith
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge, CB3 OHE, United Kingdom.
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16
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Chickering WE, Eisenstein JP, Reno JL. Hot-electron thermocouple and the diffusion thermopower of two-dimensional electrons in GaAs. PHYSICAL REVIEW LETTERS 2009; 103:046807. [PMID: 19659385 DOI: 10.1103/physrevlett.103.046807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Indexed: 05/28/2023]
Abstract
A simple hot-electron thermocouple is realized in a two-dimensional electron system (2DES) and used to measure the diffusion thermopower of the 2DES at zero magnetic field. This hot-electron technique, which requires no micron-scale patterning of the 2DES, is much less sensitive than conventional methods to phonon-drag effects. Our thermopower results are in good agreement with the Mott formula for diffusion thermopower for temperatures up to T approximately 2 K.
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Affiliation(s)
- W E Chickering
- Condensed Matter Physics, California Institute of Technology, Pasadena, California 91125, USA
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17
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Frolov SM, Venkatesan A, Yu W, Folk JA, Wegscheider W. Electrical generation of pure spin currents in a two-dimensional electron gas. PHYSICAL REVIEW LETTERS 2009; 102:116802. [PMID: 19392226 DOI: 10.1103/physrevlett.102.116802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Indexed: 05/27/2023]
Abstract
Pure spin currents are generated and detected in micron-wide channels of a GaAs two-dimensional electron gas, using quantum point contacts in an in-plane magnetic field as injectors and detectors. The enhanced sensitivity to spin transport offered by a nonlocal measurement geometry enables accurate spin current measurements in this widely studied physical system. The polarization of the contacts is used to extract the quantum point contact g factor and provides a test for spontaneous polarization at 0.7 structure. The spin relaxation length in the channel is 30-50 microm over the magnetic field range 3-10 T, much longer than has been reported in GaAs two-dimensional electron gases but shorter than that expected from Dyakonov-Perel relaxation.
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Affiliation(s)
- S M Frolov
- Department of Physics, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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18
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Granger G, Eisenstein JP, Reno JL. Observation of chiral heat transport in the quantum Hall regime. PHYSICAL REVIEW LETTERS 2009; 102:086803. [PMID: 19257768 DOI: 10.1103/physrevlett.102.086803] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Indexed: 05/27/2023]
Abstract
Heat transport in the quantum Hall regime is investigated using micron-scale heaters and thermometers positioned along the edge of a millimeter-scale two dimensional electron system (2DES). The heaters rely on localized current injection into the 2DES, while the thermometers are based on the thermoelectric effect. In the nu=1 integer quantized Hall state, a thermoelectric signal appears at an edge thermometer only when it is "downstream," in the sense of electronic edge transport, from the heater. When the distance between the heater and the thermometer is increased, the thermoelectric signal is reduced, showing that the electrons cool as they propagate along the edge.
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Affiliation(s)
- G Granger
- Condensed Matter Physics, California Institute of Technology, Pasadena, California 91125, USA
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19
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Novikov DS. Transverse field effect in graphene ribbons. PHYSICAL REVIEW LETTERS 2007; 99:056802. [PMID: 17930776 DOI: 10.1103/physrevlett.99.056802] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Indexed: 05/25/2023]
Abstract
It is shown that a graphene ribbon, a ballistic strip of carbon monolayer, may serve as a quantum wire whose electronic properties can be continuously and reversibly controlled by an externally applied transverse voltage. The electron bands of armchair-edge ribbons undergo dramatic transformations: The Fermi surface fractures, Fermi velocity and effective mass change sign, and excitation gaps are reduced by the transverse field. These effects are manifest in the conductance plateaus, van Hove singularities, thermopower, and activated transport. The control over one-dimensional bands may help enhance effects of electron correlations, and be utilized in device applications.
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Affiliation(s)
- D S Novikov
- W.I. Fine Theoretical Physics Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Lunde AM, Flensberg K, Glazman LI. Interaction-induced resonance in conductance and thermopower of quantum wires. PHYSICAL REVIEW LETTERS 2006; 97:256802. [PMID: 17280378 DOI: 10.1103/physrevlett.97.256802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2006] [Indexed: 05/13/2023]
Abstract
We study the effect of electron-electron interaction on the transport properties of short clean quantum wires adiabatically connected to reservoirs. Interactions lead to resonances in a multichannel wire at particular values of the Fermi energy. We investigate in detail the resonance in a two-channel wire. The (negative) conductance correction peaks at the resonance, and decays exponentially as the Fermi energy is tuned away, the resonance width being given by the temperature. Likewise, the thermopower shows a characteristic structure, which is surprisingly well approximated by the so-called Mott formula. Finally, fourfold splitting of the resonance in a magnetic field provides a unique signature of the effect.
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Affiliation(s)
- Anders Mathias Lunde
- Nano-Science Center, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
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Leturcq R, Sánchez D, Götz G, Ihn T, Ensslin K, Driscoll DC, Gossard AC. Magnetic field symmetry and phase rigidity of the nonlinear conductance in a ring. PHYSICAL REVIEW LETTERS 2006; 96:126801. [PMID: 16605938 DOI: 10.1103/physrevlett.96.126801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Indexed: 05/08/2023]
Abstract
We have performed nonlinear transport measurements as a function of a perpendicular magnetic field in a semiconductor Aharonov-Bohm ring connected to two leads. While the voltage-symmetric part of the conductance is symmetric in the magnetic field, the voltage-antisymmetric part of the conductance is not symmetric. These symmetry relations are compatible with the scattering theory for nonlinear mesoscopic transport. The observed asymmetry can be tuned continuously by changing the gate voltages near the arms of the ring, showing that the phase of the nonlinear conductance in a two-terminal interferometer is not rigid, in contrast with the case for the linear conductance.
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Affiliation(s)
- R Leturcq
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland.
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Scheibner R, Buhmann H, Reuter D, Kiselev MN, Molenkamp LW. Thermopower of a Kondo spin-correlated quantum dot. PHYSICAL REVIEW LETTERS 2005; 95:176602. [PMID: 16383850 DOI: 10.1103/physrevlett.95.176602] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Indexed: 05/05/2023]
Abstract
The thermopower of a Kondo-correlated gate-defined quantum dot is studied using a current heating technique. In the presence of spin correlations, the thermopower shows a clear deviation from the semiclassical Mott relation between thermopower and conductivity. The strong thermopower signal indicates a significant asymmetry in the spectral density of states of the Kondo resonance with respect to the Fermi energies of the reservoirs. The observed behavior can be explained within the framework of an Anderson-impurity model.
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Affiliation(s)
- R Scheibner
- Physikalisches Institut (EP3), Universität Würzburg, 97074 Würzburg, Germany
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Lunde AM, Flensberg K. On the Mott formula for the thermopower of non-interacting electrons in quantum point contacts. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2005; 17:3879-3884. [PMID: 21690704 DOI: 10.1088/0953-8984/17/25/014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We calculate the linear response thermopower S of a quantum point contact using the Landauer formula and therefore assume non-interacting electrons. The purpose of the paper is to compare analytically and numerically the linear thermopower S of non-interacting electrons to the low-temperature approximation, [Formula: see text], and the so-called Mott expression, [Formula: see text], where G(μ,T) is the (temperature-dependent) conductance. This comparison is important, since the Mott formula is often used to detect deviations from single-particle behaviour in the thermopower of a point contact.
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Humphrey TE, Newbury R, Taylor RP, Linke H. Reversible quantum brownian heat engines for electrons. PHYSICAL REVIEW LETTERS 2002; 89:116801. [PMID: 12225160 DOI: 10.1103/physrevlett.89.116801] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2001] [Indexed: 05/23/2023]
Abstract
Brownian heat engines use local temperature gradients in asymmetric potentials to move particles against an external force. The energy efficiency of such machines is generally limited by irreversible heat flow carried by particles that make contact with different heat baths. Here we show that, by using a suitably chosen energy filter, electrons can be transferred reversibly between reservoirs that have different temperatures and electrochemical potentials. We apply this result to propose heat engines based on mesoscopic semiconductor ratchets, which can quasistatically operate arbitrarily close to Carnot efficiency.
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Affiliation(s)
- T E Humphrey
- School of Physics, University of New South Wales, UNSW Sydney 2052, Australia
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Bogachek EN, Scherbakov AG, Landman U. Thermopower of quantum nanowires in a magnetic field. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:R11094-R11097. [PMID: 9984994 DOI: 10.1103/physrevb.54.r11094] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Lin MF, Chuu DS, Shung KW. Thermal conductance and the Peltier coefficient of carbon nanotubes. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:11186-11192. [PMID: 9982693 DOI: 10.1103/physrevb.53.11186] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Edwards HL, Niu Q, Georgakis GA. Cryogenic cooling using tunneling structures with sharp energy features. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:5714-5736. [PMID: 9981758 DOI: 10.1103/physrevb.52.5714] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Taboryski R, Brosh B, Simmons MY, Ritchie DA, Ford CJ, Pepper M. Magnetothermopower oscillations in a lateral superlattice. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:17243-17246. [PMID: 9978747 DOI: 10.1103/physrevb.51.17243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Guttman GD, Ben-Jacob E, Bergman DJ. Thermopower of mesoscopic and disordered systems. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:17758-17766. [PMID: 9978809 DOI: 10.1103/physrevb.51.17758] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Afonin VV, Rudin AM. Thermoelectric resonant transport through the Anderson impurities. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:18025-18028. [PMID: 9978847 DOI: 10.1103/physrevb.51.18025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Molenkamp LW. Hydrodynamic electron flow in high-mobility wires. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:13389-13402. [PMID: 9978143 DOI: 10.1103/physrevb.51.13389] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Taboryski R, Kristensen A, Sorensen CB, Lindelof PE. Conductance-quantization broadening mechanisms in quantum point contacts. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:2282-2286. [PMID: 9978979 DOI: 10.1103/physrevb.51.2282] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chu CS, Chou MH. Effects of an impurity on the conductance and thermopower of a saddle-point-potential quantum point contact. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:14212-14222. [PMID: 9975642 DOI: 10.1103/physrevb.50.14212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Mao JM, Xie SS, Gu BY, Yang GZ. Far-infrared radiation-induced inter-edge-channel scattering in a high magnetic field. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:10924-10931. [PMID: 9975196 DOI: 10.1103/physrevb.50.10924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kozub VI, Rudin AM. Phonon-drag thermopower of quantum point contacts. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:2681-2684. [PMID: 9976497 DOI: 10.1103/physrevb.50.2681] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Liefrink F, Dijkhuis JI, Molenkamp LW. Experimental study of reduced shot noise in a diffusive mesoscopic conductor. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:14066-14069. [PMID: 10010370 DOI: 10.1103/physrevb.49.14066] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Molenkamp LW. Electron-electron-scattering-induced size effects in a two-dimensional wire. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:5038-5041. [PMID: 10011442 DOI: 10.1103/physrevb.49.5038] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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DiVincenzo DP. Fluctuating local thermoelectric heat in dirty metals. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:1404-1408. [PMID: 10008500 DOI: 10.1103/physrevb.48.1404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Lesovik GB, Presilla C. Nonlinear voltages in multiple-lead coherent conductors. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:2398-2401. [PMID: 10006282 DOI: 10.1103/physrevb.47.2398] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Beenakker CW, Staring AA. Theory of the thermopower of a quantum dot. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:9667-9676. [PMID: 10002777 DOI: 10.1103/physrevb.46.9667] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Peeters FM, Vasilopoulos P. Electrical and thermal properties of a two-dimensional electron gas in a one-dimensional periodic potential. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:4667-4680. [PMID: 10004224 DOI: 10.1103/physrevb.46.4667] [Citation(s) in RCA: 149] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Okuyama Y, Tokuda N. Thermoelectric power of a narrow constriction in the adiabatic approximation. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:2610-2612. [PMID: 10003941 DOI: 10.1103/physrevb.46.2610] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Molenkamp LW, Gravier T, Buijk OJ, Mabesoone MA, Foxon CT. Peltier coefficient and thermal conductance of a quantum point contact. PHYSICAL REVIEW LETTERS 1992; 68:3765-3768. [PMID: 10045791 DOI: 10.1103/physrevlett.68.3765] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Palacios JJ, Tejedor C. Magnetic-field effects on the transport coefficients of a quantum point contact. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:13725-13728. [PMID: 10001470 DOI: 10.1103/physrevb.45.13725] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Proetto CR. Thermopower oscillations of a quantum-point contact. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 44:9096-9099. [PMID: 9998882 DOI: 10.1103/physrevb.44.9096] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Yamada S, Yamamoto M. Quantum oscillation of transverse resistance and resistance reciprocity as a point-contact boundary problem. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 43:9369-9372. [PMID: 9996630 DOI: 10.1103/physrevb.43.9369] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kearney MJ, Syme RT, Pepper M. Observation of quantum interference in thermoelectric transport. PHYSICAL REVIEW LETTERS 1991; 66:1622-1625. [PMID: 10043257 DOI: 10.1103/physrevlett.66.1622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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