51
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Reynoso AA, Usaj G, Balseiro CA, Feinberg D, Avignon M. Anomalous Josephson current in junctions with spin polarizing quantum point contacts. PHYSICAL REVIEW LETTERS 2008; 101:107001. [PMID: 18851244 DOI: 10.1103/physrevlett.101.107001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Indexed: 05/26/2023]
Abstract
We consider a ballistic Josephson junction with a quantum point contact in a two-dimensional electron gas with Rashba spin-orbit coupling. The point contact acts as a spin filter when embedded in a circuit with normal electrodes. We show that with an in-plane external magnetic field an anomalous supercurrent appears even for zero phase difference between the superconducting electrodes. In addition, the external field induces large critical current asymmetries between the two flow directions, leading to supercurrent rectifying effects.
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Affiliation(s)
- A A Reynoso
- Instituto Balseiro, Centro Atómico Bariloche, Río Negro, Argentina
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52
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Liang Q, Dong J. Superconducting switch made of graphene-nanoribbon junctions. NANOTECHNOLOGY 2008; 19:355706. [PMID: 21828860 DOI: 10.1088/0957-4484/19/35/355706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The transmission of superconductor-graphene nanoribbon-superconductor junctions (SGS) has been studied by the non-equilibrium Green's function method. It is found that the on-site potential U in the center zigzag graphene nanoribbon (ZGNR) of the SGS junction plays an important role in the magnitude of the supercurrent I(c). As the effective Fermi energy μ(eff) (μ(eff) = μ(F)-U) goes from negative to positive, the SGS junction would suddenly transform from an 'OFF' state to an 'ON' state. And, as μ(eff) increases further, the I(c) will continue to increase. This switching behavior of the SGS junction shares the same origin with the zigzag GNR valley-isospin valve (Rycerz et al 2007 Nat. Phys. 3 172). Besides the valley-isospin, the density of states will also have an effect on the suppression of I(c).
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Affiliation(s)
- Qifeng Liang
- Group of Computational Condensed Matter Physics, National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
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53
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Sköldberg J, Löfwander T, Shumeiko VS, Fogelström M. Spectrum of Andreev bound states in a molecule embedded inside a microwave-excited superconducting junction. PHYSICAL REVIEW LETTERS 2008; 101:087002. [PMID: 18764650 DOI: 10.1103/physrevlett.101.087002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Indexed: 05/26/2023]
Abstract
Nondissipative Josephson current through nanoscale superconducting constrictions is carried by spectroscopically sharp energy states, the so-called Andreev states. Although theoretically predicted almost 40 years ago, no direct spectroscopic evidence of these Andreev bound states exists to date. We propose a novel type of spectroscopy based on embedding a superconducting constriction, formed by a single-level molecule junction, in a microwave QED cavity environment. In the electron-dressed cavity spectrum we find a polariton excitation at twice the Andreev bound state energy, and a superconducting-phase-dependent ac Stark shift of the cavity frequency. Dispersive measurement of this frequency shift can be used for Andreev bound state spectroscopy.
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Affiliation(s)
- Jonas Sköldberg
- Department of Microtechnology and Nanoscience--MC2, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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54
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Tunable double dots and Kondo enhanced Andreev transport in InAs nanowires. ACTA ACUST UNITED AC 2008. [DOI: 10.1116/1.2839634] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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55
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Della Rocca ML, Chauvin M, Huard B, Pothier H, Esteve D, Urbina C. Measurement of the current-phase relation of superconducting atomic contacts. PHYSICAL REVIEW LETTERS 2007; 99:127005. [PMID: 17930546 DOI: 10.1103/physrevlett.99.127005] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Indexed: 05/25/2023]
Abstract
We have probed the current-phase relation of an atomic contact placed with a tunnel junction in a small superconducting loop. The measurements are in quantitative agreement with the predictions of a resistively shunted SQUID model in which the Josephson coupling of the contact is calculated using the independently determined transmissions of its conduction channels.
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Affiliation(s)
- M L Della Rocca
- Quantronics group, Service de Physique de l'Etat Condensé (CNRS URA 2464) DSM/DRECAM, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
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56
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Sand-Jespersen T, Paaske J, Andersen BM, Grove-Rasmussen K, Jørgensen HI, Aagesen M, Sørensen CB, Lindelof PE, Flensberg K, Nygård J. Kondo-enhanced Andreev tunneling in InAs nanowire quantum dots. PHYSICAL REVIEW LETTERS 2007; 99:126603. [PMID: 17930535 DOI: 10.1103/physrevlett.99.126603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2007] [Indexed: 05/25/2023]
Abstract
We report measurements of the nonlinear conductance of InAs nanowire quantum dots coupled to superconducting leads. We observe a clear alternation between odd and even occupation of the dot, with subgap peaks at |V(sd)| = Delta/e markedly stronger (weaker) than the quasiparticle tunneling peaks at |V(sd)| = 2Delta/e for odd (even) occupation. We attribute the enhanced Delta peak to an interplay between Kondo correlations and Andreev tunneling in dots with an odd number of spins, and we substantiate this interpretation by a poor man's scaling analysis.
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Affiliation(s)
- T Sand-Jespersen
- Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
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57
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Chauvin M, vom Stein P, Esteve D, Urbina C, Cuevas JC, Yeyati AL. Crossover from Josephson to multiple Andreev reflection currents in atomic contacts. PHYSICAL REVIEW LETTERS 2007; 99:067008. [PMID: 17930862 DOI: 10.1103/physrevlett.99.067008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Indexed: 05/25/2023]
Abstract
The basic current-carrying mechanism through a superconducting weak link embedded in a resistive environment undergoes a continuous crossover, as the voltage increases, from Josephson Cooper pair transfer exciting electromagnetic modes in the environment to multiple Andreev reflections leading to the creation of quasiparticles. We corroborate these ideas through measurements of the dc current-voltage characteristics of superconducting atomic contacts containing channels of arbitrary and adjustable transmission. We present a simple model, in the spirit of the classical resistively shunted junction model, that accounts well for the observed characteristics.
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Affiliation(s)
- M Chauvin
- Quantronics Group, Service de Physique de l'Etat Condensé (CNRS URA 2464), DSM/DRECAM/SPEC, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
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58
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Marchenkov A, Dai Z, Donehoo B, Barnett RN, Landman U. Alternating current Josephson effect and resonant superconducting transport through vibrating Nb nanowires. NATURE NANOTECHNOLOGY 2007; 2:481-485. [PMID: 18654344 DOI: 10.1038/nnano.2007.218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 06/21/2007] [Indexed: 05/26/2023]
Abstract
In 1962, Josephson made a celebrated prediction: when a constant voltage is applied across a thin insulator separating two superconductors, it will generate an oscillating current. These oscillations are ubiquitous in superconducting weak links of various geometries, and analogues have been found in other macroscopic quantum systems, such as superfluids and gaseous Bose-Einstein condensates. The interplay between the oscillating current and external microwave radiation of matching frequency (Shapiro steps) or with internal electrodynamic resonances (Fiske effect) appear as changes in the current-voltage characteristics of superconducting tunnel junctions and provide further insight into the phenomenon. Here, we report measurements and theoretical studies suggesting that Josephson current oscillations interact with atomic-scale mechanical motion as well. We formed a niobium dimer nanowire that acts as a weak link between two superconducting (bulk) niobium electrodes. We find features in the differential conductance through the dimer which we believe correspond to excitations of the dimer vibrational modes by Josephson oscillations and support our results with theoretical simulations.
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59
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Zhao E, Sauls JA. Dynamics of spin transport in voltage-biased Josephson junctions. PHYSICAL REVIEW LETTERS 2007; 98:206601. [PMID: 17677724 DOI: 10.1103/physrevlett.98.206601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Indexed: 05/16/2023]
Abstract
We investigate spin transport in voltage-biased spin-active Josephson junctions. The interplay of spin filtering, spin mixing, and multiple Andreev reflection leads to nonlinear voltage dependence of the dc and ac spin current. We compute the voltage characteristics of the spin current (IS) for superconductor-ferromagnet-superconductor Josephson junctions. The subharmonic gap structure of IS(V) is shown to be sensitive to the degree of spin mixing generated by the ferromagnetic interface, and exhibits a pronounced even-odd effect associated with spin transport during multiple Andreev reflection processes. For strong spin mixing both the magnitude and the direction of the dc spin current can be sensitively controlled by the bias voltage.
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Affiliation(s)
- Erhai Zhao
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA
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60
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Chauvin M, vom Stein P, Pothier H, Joyez P, Huber ME, Esteve D, Urbina C. Superconducting atomic contacts under microwave irradiation. PHYSICAL REVIEW LETTERS 2006; 97:067006. [PMID: 17026194 DOI: 10.1103/physrevlett.97.067006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Indexed: 05/12/2023]
Abstract
We have measured the effect of microwave irradiation on the dc current-voltage characteristics of superconducting atomic contacts. The interaction of the external field with the ac supercurrents leads to replicas of the supercurrent peak, the well-known Shapiro resonances. The observation of supplementary fractional resonances for contacts containing highly transmitting conduction channels reveals their nonsinusoidal current-phase relation. The resonances sit on a background current which is itself deeply modified, as a result of photon-assisted multiple Andreev reflections. The results provide firm support for the full quantum theory of transport between two superconductors based on the concept of Andreev bound states.
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Affiliation(s)
- M Chauvin
- Quantronics Group, Service de Physique de l'Etat Condensé (CNRS URA 2464), DSM/DRECAM, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
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61
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Jørgensen HI, Grove-Rasmussen K, Novotný T, Flensberg K, Lindelof PE. Electron transport in single-wall carbon nanotube weak links in the Fabry-Perot regime. PHYSICAL REVIEW LETTERS 2006; 96:207003. [PMID: 16803198 DOI: 10.1103/physrevlett.96.207003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Indexed: 05/10/2023]
Abstract
We fabricated reproducible high transparency superconducting contacts consisting of superconducting Ti/Al/Ti trilayers to gated single-wall carbon nanotubes. The reported semiconducting single-wall carbon nanotubes have normal state differential conductance up to 3e2/h and exhibit clear Fabry-Perot interference patterns in the bias spectroscopy plot. We observed subharmonic gap structure in the differential conductance and a distinct peak in the conductance at zero bias, which is interpreted as a manifestation of the supercurrent. The gate dependence of this supercurrent as well as the excess current are examined and compared to the coherent theory of superconducting quantum point contacts with good agreement.
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Affiliation(s)
- H I Jørgensen
- Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
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62
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Levy Yeyati A, Cuevas JC, Martín-Rodero A. Dynamical coulomb blockade of multiple Andreev reflections. PHYSICAL REVIEW LETTERS 2005; 95:056804. [PMID: 16090903 DOI: 10.1103/physrevlett.95.056804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Indexed: 05/03/2023]
Abstract
We analyze the dynamical Coulomb blockade of multiple Andreev reflections (MAR) in a superconducting quantum point contact coupled to a macroscopic impedance. We find that at very low transmission the blockade scales as n2 with n = Int(2delta/eV), where V is the bias voltage and delta is the superconducting gap, as it would correspond to the occurrence of shots of charge ne. For higher transmission the blockade is reduced because of both the Pauli principle and the elastic renormalization of the MAR probability, and for certain voltage regions it may even become an anti-blockade; i.e., the current is enhanced due to the coupling with the electromagnetic environment.
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Affiliation(s)
- A Levy Yeyati
- Departamento de Física Teórica de la Materia Condensada CV, Universidad Autónoma de Madrid, E28049 Madrid, Spain
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63
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Uzawa Y, Wang Z. Coherent multiple charge transfer in a superconducting NbN tunnel junction. PHYSICAL REVIEW LETTERS 2005; 95:017002. [PMID: 16090645 DOI: 10.1103/physrevlett.95.017002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Indexed: 05/03/2023]
Abstract
We measured shot noise and submillimeter-wave response in a superconducting NbN tunnel junction that had a subharmonic gap structure on the current-voltage (I-V) curve. We found that the observed effective charge, defined from the noise-current ratio, tends to a steplike function of voltage. In the presence of submillimeter-wave radiation of frequency v, novel step structures spaced by hv/2e below and above the half-gap voltage clearly appeared on the I-V curve, overlapping the ordinary photon-assisted tunneling steps spaced by hv/e. Observation of these features provides clear evidence that coherent multiple Andreev reflection processes occur in the NbN tunnel junction with low barrier transparency.
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Affiliation(s)
- Y Uzawa
- Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
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64
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Bolech CJ, Giamarchi T. Point-contact tunneling involving low-dimensional spin-triplet superconductors. PHYSICAL REVIEW LETTERS 2004; 92:127001. [PMID: 15089699 DOI: 10.1103/physrevlett.92.127001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2003] [Indexed: 05/24/2023]
Abstract
We modify and extend previous microscopic calculations of tunneling in superconducting junctions based on a nonequilibrium Green function formalism to include the case of spin-triplet pairing. We show that distinctive features are present in the I-V characteristics of different kinds of junctions, in particular, when the effects of magnetic fields are taken into account, that permit to identify the type of pairing. We discuss the relevance of these results in the context of quasi-one-dimensional organic superconductors such as (TMTSF)2PF6 and layered compounds like Sr2RuO(4).
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Affiliation(s)
- C J Bolech
- Université de Genève, DPMC, 24 Quai Ernest Ansermet, CH-1211 Genève 4, Switzerland
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65
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Yeyati AL, Martín-Rodero A, Vecino E. Nonequilibrium dynamics of Andreev states in the Kondo regime. PHYSICAL REVIEW LETTERS 2003; 91:266802. [PMID: 14754078 DOI: 10.1103/physrevlett.91.266802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Indexed: 05/24/2023]
Abstract
The transport properties of a quantum dot coupled to superconducting leads are analyzed. It is shown that the quasiparticle current in the Kondo regime is determined by the nonequilibrium dynamics of subgap states (Andreev states) under an applied voltage. The current at low bias is suppressed exponentially for decreasing Kondo temperature in agreement with recent experiments. We also predict novel interference effects due to multiple Landau-Zener transitions between Andreev states.
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Affiliation(s)
- A Levy Yeyati
- Departamento de Física Teórica de la Materia Condensada CV, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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66
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Cuevas JC, Belzig W. Full counting statistics of multiple Andreev reflections. PHYSICAL REVIEW LETTERS 2003; 91:187001. [PMID: 14611306 DOI: 10.1103/physrevlett.91.187001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Indexed: 05/24/2023]
Abstract
We derive the full distribution of transmitted particles through a superconducting point contact of arbitrary transparency under voltage bias. The charge transport is dominated by multiple Andreev reflections. The counting statistics is a multinomial distribution of processes, in which multiple charges ne (n=1,2,3, ...) are transferred through the contact. For zero temperature we obtain analytical expressions for the probabilities of the multiple Andreev reflections. The current, shot noise, and high current cumulants in a variety of situations can be obtained from our result.
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Affiliation(s)
- J C Cuevas
- Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany
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67
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Cuevas JC, Heurich J, Martín-Rodero A, Levy Yeyati A, Schön G. Subharmonic shapiro steps and assisted tunneling in superconducting point contacts. PHYSICAL REVIEW LETTERS 2002; 88:157001. [PMID: 11955213 DOI: 10.1103/physrevlett.88.157001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2001] [Indexed: 05/23/2023]
Abstract
We analyze the current in a superconducting point contact of arbitrary transmission in the presence of a microwave radiation. The interplay between the ac Josephson current and the microwave signal gives rise to Shapiro steps at voltages V = (m/n)h(omega)(r)/2e, where n,m are integer numbers and omega(r) is the radiation frequency. The subharmonic steps (n not equal 1) are a consequence of multiple Andreev reflections (MAR) and provide a signature of the peculiar ac Josephson effect at high transmission. Moreover, the dc current exhibits a rich subgap structure due to photon-assisted MARs.
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Affiliation(s)
- J C Cuevas
- Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe, Germany
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68
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Dubos P, Courtois H, Buisson O, Pannetier B. Coherent low-energy charge transport in a diffusive S-N-S junction. PHYSICAL REVIEW LETTERS 2001; 87:206801. [PMID: 11690503 DOI: 10.1103/physrevlett.87.206801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2001] [Indexed: 05/23/2023]
Abstract
We have studied the current-voltage characteristics of diffusive mesoscopic Nb-Cu-Nb Josephson junctions with highly transparent Nb-Cu interfaces. We consider the low-voltage and high-temperature regime eV < epsilon(c) < k(B)T, where epsilon(c) is the Thouless energy. The observed excess current as well as the observed subharmonic Shapiro steps under microwave irradiation suggest the occurrence of low-energy coherent multiple Andreev reflection.
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Affiliation(s)
- P Dubos
- Centre de Recherches sur les Très Basses Températures, C.N.R.S., associé à l'Université Joseph Fourier, 25 Av. des Martyrs, 38042 Grenoble, France
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69
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Yeyati AL, Martin-Rodero A, Esteve D, Urbina C. Direct link between Coulomb blockade and shot noise in a quantum-coherent structure. PHYSICAL REVIEW LETTERS 2001; 87:046802. [PMID: 11461634 DOI: 10.1103/physrevlett.87.046802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2001] [Indexed: 05/23/2023]
Abstract
We analyze the current-voltage characteristic of a quantum conduction channel coupled to an electromagnetic environment with arbitrary frequency-dependent impedance. In the weak blockade regime the correction to the Ohmic behavior is directly related to the channel current fluctuations, vanishing at perfect transmission in the same way as shot noise. This relation can be generalized to describe the environmental Coulomb blockade in a generic mesoscopic conductor coupled to an external impedance, as the response of the latter to the current fluctuations in the former.
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Affiliation(s)
- A L Yeyati
- Departamento de Física Teórica de la Materia Condensada C-V, Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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70
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Cron R, Goffman MF, Esteve D, Urbina C. Multiple-charge-quanta shot noise in superconducting atomic contacts. PHYSICAL REVIEW LETTERS 2001; 86:4104-4107. [PMID: 11328106 DOI: 10.1103/physrevlett.86.4104] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2000] [Indexed: 05/23/2023]
Abstract
We have measured shot noise in aluminum atomic point contacts containing a small number of conduction channels of known transmissions. In the normal state, we find that the noise power is reduced from its Poissonian value and reaches the partition limit, as calculated from the transmissions. In the superconducting state, the noise reveals the large effective charge associated with each elementary transfer process, in excellent agreement with the predictions of the quantum theory of multiple Andreev reflections.
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Affiliation(s)
- R Cron
- Service de Physique de l'Etat Condensé, Commissariat à l'Energie Atomique, Saclay, F-91191 Gif-sur-Yvette Cedex, France
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71
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Bai ZM, Wang YR, Ge ML. Electric current and conductance in a chain of quantum dots. ACTA ACUST UNITED AC 2001. [DOI: 10.1088/0305-4470/34/8/306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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72
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Scheer E, Belzig W, Naveh Y, Devoret MH, Esteve D, Urbina C. Proximity effect and multiple Andreev reflections in gold atomic contacts. PHYSICAL REVIEW LETTERS 2001; 86:284-287. [PMID: 11177812 DOI: 10.1103/physrevlett.86.284] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2000] [Indexed: 05/23/2023]
Abstract
We investigate the electronic transport properties of gold point contacts with superconducting aluminum leads. The modifications induced by the proximity effect in the quasiparticle density of states at the contact region are measured by tunnel spectroscopy. The theory of transport through multiple Andreev reflections is extended to incorporate these effects and used to determine the number and transmission coefficients of the conduction channels in the contact regime. We find that the smallest contacts, formed by one gold atom between the electrodes, contribute one single channel to the transport with variable transmission T between 0.1 and 1.
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Affiliation(s)
- E Scheer
- Physikalisches Institut, Universität Karlsruhe, Germany
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73
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74
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Scheer E, Agraït N, Cuevas JC, Yeyati AL, Ludoph B, Martín-Rodero A, Bollinger GR, van Ruitenbeek JM, Urbina C. The signature of chemical valence in the electrical conduction through a single-atom contact. Nature 1998. [DOI: 10.1038/28112] [Citation(s) in RCA: 555] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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