Decay Lengths for Diffusive Transport Activated by Andreev Reflections in Al/<i>n</i>-GaAs/Al Superconductor-Semiconductor-Superconductor Junctions

Kutchinsky, Jonatan; Taboryski, Rafael J.; Clausen, Thomas; Sørensen, C. B.; Lindelöf, P. E.; Hansen, Jørn Bindslev; Jacobsen, Claus J. H.; Skov, J. L.

doi:10.1103/physrevlett.78.931

Cited by 58 publications

(50 citation statements)

References 19 publications

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“…The peak voltages nicely match the BCS curve with a slightly reduced gap. Being governed by L (T), 8 the amplitude of the MAR features shows a relatively weak temperature dependence. This is in contrast to the supercurrent which strongly varies with temperature as expected from the exponential dependence of the Josephson coupling on L T .…”

Section: Alõcuõal Junctionsmentioning

confidence: 99%

“…In particular for small applied voltages eVӶ⌬ quasiparticles have to climb up to the energy gap ⌬ via multiple Andreev reflections ͑MAR͒ at the two SN boundaries in order to remove the deposited energy into the reservoirs. For samples shorter than the phase coherence length L subharmonic gap structures have been observed in diffusive samples 8 in the differential conductance dI/dV at voltages close to Vϭ2⌬/en where n counts the number of reflections in the MAR cycle. Such structures have been found earlier in superconducting microbridges, tunnel junctions and ballistic S/N/S point contacts.…”

Section: Introductionmentioning

confidence: 99%

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Multiple Andreev reflection and giant excess noise in diffusive superconductor/normal-metal/superconductor junctions

et al. 2000

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We have studied superconductor/normal-metal/superconductor (SNS) junctions consisting of short Au or Cu wires between Nb or Al banks. The Nb based junctions display inherent electron heating effects induced by the high thermal resistance of the NS boundaries. The Al based junctions show in addition subharmonic gap structures in the differential conductance dI/dV and a pronounced peak in the excess noise at very low voltages V. We suggest that the noise peak is caused by fluctuations of the supercurrent at the onset of Josephson coupling between the superconducting banks. At intermediate temperatures where the supercurrent is suppressed a noise contribution ϰ1/V remains, which suggests the presence of a long-range proximity effect in the noise.

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Section: Alõcuõal Junctionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiple Andreev reflection and giant excess noise in diffusive superconductor/normal-metal/superconductor junctions

et al. 2000

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“…13 For example, the appearance of the zero bias conductance peak ͑ZBCP͒ in DN/S junctions is a direct consequence of the interference effect of a quasiparticle in DN. [14][15][16][17][18][19][20][21][22][23][24] To study such interference effects, the quasiclassical Green's function theory [25][26][27] has been widely used because of its convenience and broad applicability. Based on this formalism, theory of charge transport in DN/S junctions was formulated by Volkov, Zaitsev, and Klapwijk ͑VZK͒.…”

Section: Introductionmentioning

confidence: 99%

Theory of thermal and charge transport in diffusive normal metal/superconductor junctions

et al. 2005

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Thermal and charge transport in diffusive normal metal ͑DN͒/insulator/s-, d-, and p-wave superconductor junctions are studied based on the Usadel equation with the Nazarov's generalized boundary condition. We derive a general expression of the thermal conductance in unconventional superconducting junctions. Thermal conductance, electric conductance of junctions and their Lorentz ratio are calculated as a function of resistance in DN, the Thouless energy, magnetic scattering rate in DN and transparency of the insulating barrier. We also discuss transport properties for various orientation angles between the normal to the interface and the crystal axis of superconductors. It is demonstrated that the proximity effect does not influence the thermal conductance while the midgap Andreev resonant states suppress it. Dependencies of the electrical and thermal conductance on temperature are sensitive to pairing symmetries and orientation angles. The results imply a possibility to distinguish one pairing symmetry from another based on the results of experimental observations.

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“…As a result, the conductance spectra of mesoscopic junctions may be significantly modified by these interference effects. A remarkable experimental manifestation of the electron-hole phase coherence is the observation of the zero bias conductance peak (ZBCP) in diffusive normal metal (N)/superconductor (S) tunneling junctions [74][75][76][77][78][79][80][81][82][83][84].…”

Section: Theory Of Charge Transport In Diffusive Normal Metal/high-t mentioning

confidence: 99%

Impurity scattering effect on charge transport in high-Tc cuprate junctions

Tanaka

Asano

Kashiwaya

2004

Low Temperature Physics

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It is known that the zero-bias conductance peak (ZBCP) is expected in tunneling spectra of normal-metal/high-T c cuprate junctions because of the formation of the midgap Andreev resonant states (MARS) at junction interfaces. In the present review, we report the recent theoretical study of impurity scattering effects on the tunneling spectroscopy. In the former part of the present paper, we discuss impurity effects in normal metal. We calculate tunneling conductance for diffusive normal metal (DN)/high T c cuprate junctions based on the Keldysh Green's function technique. Besides the ZBCP due to the MARS, we can expect ZBCP caused by the different origin, i.e., the coherent Andreev reflection (CAR) assisted by the proximity effect in DN. Their relative importance depends on the angle a between the interface normal and the crystal axis of high-T c superconductors. At a = 0, we find the ZBCP by the CAR for low transparent junctions with small Thouless energies in DN; this is similar to the case of diffusive normal metal/insulator/s-wave superconductor junctions. Under increase of a from zero to p/4, the contribution of MARS to ZBCP becomes more prominent and the effect of the CAR is gradually suppressed. Such complex spectral features would be observable in conductance spectra of high-T c junctions at very low temperatures. In the latter part of our paper, we study impurity effects in superconductors. We consider impurities near the junction interface on the superconductor side. The conductance is calculated from the Andreev and the normal reflection coefficients which are estimated by using the single-site approximation in an analytic calculation and by the recursive Green function method in a numerical simulation. We find splitting of the ZBCP in the presence of the time reversal symmetry. Thus the zero-field splitting of ZBCP in the experiment does not perfectly prove an existence of broken time reversal symmetry state.

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Decay Lengths for Diffusive Transport Activated by Andreev Reflections in Al/n-GaAs/Al Superconductor-Semiconductor-Superconductor Junctions

Cited by 58 publications

References 19 publications

Multiple Andreev reflection and giant excess noise in diffusive superconductor/normal-metal/superconductor junctions

Multiple Andreev reflection and giant excess noise in diffusive superconductor/normal-metal/superconductor junctions

Theory of thermal and charge transport in diffusive normal metal/superconductor junctions

Impurity scattering effect on charge transport in high-Tc cuprate junctions

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