Crossover from mesoscopic to classical proximity effects, induced by particle - hole symmetry breaking in Andreev interferometers

Volkov, A. N.; Allsopp, N. K.; Lambert, Colin J.

doi:10.1088/0953-8984/8/4/001

Cited by 75 publications

(90 citation statements)

References 41 publications

(77 reference statements)

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“…28 By applying the VZK theory, a number of authors investigated theoretically charge transport in various proximity structures. [28][29][30][31][32][33][34][35][36][37][38][39] This work was based on the boundary conditions for the KeldyshNambu Green's function at the DN/S interface derived by Kupriyanov and Lukichev ͑KL͒ 40 from Zaitsev's boundary condition 41 in the isotropic limit. The KL boundary conditions were recently extended by Nazarov within the circuit theory 42 and applied by Tanaka et al 43 to the study of charge transport in N/S junctions with arbitrary interface transparency in order to investigate more complex structures.…”

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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Section: Introductionmentioning

confidence: 99%

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

et al. 2005

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“…In the last few years a large number of Andreev interferometers have been studied both theoretically [5][6][7][8][9][10][11] and experimentally. [12][13][14][15] Particularly the experiment of Ref.…”

Section: Introductionmentioning

confidence: 99%

Kinetic-equation approach to diffusive superconducting hybrid devices

Stoof

Nazarov

1996

Phys. Rev. B

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We present calculations of the temperature-dependent electrostatic and chemical potential distributions in disordered normal metal-superconductor structures. We show that they differ appreciably in the presence of a superconducting terminal and propose an experiment to measure these two different potential distributions. We also compute the resistance change in these structures due to a recently proposed mechanism which causes a finite effect at zero temperature. The relative resistance change due to this effect is of the order of the interaction parameter in the normal metal. Finally a detailed calculation of the resistance change due to the temperature dependence of Andreev reflection in diffusive systems is presented. We find that the maximal magnitude due to this thermal effect is in general much larger than the magnitude of the interaction effect.

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“…Although they differ slightly from each other, in the limit l 1 << 1 (l 1 = L 1 /L) the formulae for the conductances of these systems are identical. We assume the metals are diffusive and employ the well developed quasiclassical Green's function technique (see for example [15]) which has been widely used for studying transport phenomena in S/N mesoscopic structures [2][3][4][5][6]8,[16][17][18][19]7,20,21]. Using the Keldysh formalism, the conductance variation of the structure shown in Fig.…”

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Anomalous transport in normal-superconducting and ferromagnetic-superconducting nanostructures

1999

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We have calculated the temperature dependence of the conductance variation (δS(T )) of mesoscopic superconductor normal metal(S/N) structures, in the diffusive regime, analysing both weak and strong proximity effects. We show that in the case of a weak proximity effect there are two peaks in the dependence of δS(T ) on temperature. One of them (known from previous studies) corresponds to a temperature T1 of order of the Thouless energy (ǫ T h ), and another, newly predicted maximum, occurs at a temperature T2 where the energy gap in the superconductor ∆(T2) is of order ǫ T h . In the limit L φ < L the temperature T1 is determined by Dh/L 2 φ (L φ is the phase breaking length), and not ǫ T h . We have also calculated the voltage dependence δS(V ) for a S/F structure (F is a ferromagnet) and predict non-monotonic behaviour at voltages of order the Zeeman splitting.Pacs numbers: 74.25.fy, 72.10Bg, 73.40Gk, 74.50.+r Since the late 1970's it has been known that the conductance (G) of S/N mesoscopic structures depends on temperature (T ) (and voltage (V )) in a non-monotonic way (see reviews [1,2]). This behaviour was first predicted in Ref.[3] where a simple point S/N contact was analysed. The authors of Ref.[3], using a microscopic theory and assuming that the energy gap in the superconductor (∆) is much less than the Thouless energy ǫ T h ≡hD/L 2 (D is the diffusion constant), showed that the zero-bias conductance G coincides at zero temperature with its normal state value (G n ). With increasing T , G exhibits a non-monotonic behaviour, increasing to a maximum of G max ≈ 1.25G n at T m ≈ ∆(T m ) and then decreasing to G n for T > T m .Recently mesoscopic S/N structures have been fabricated in which the limit ∆ >> ǫ T h is realised. In this case Nazarov and Stoof [4] (also see [5][6][7]) argued that the temperature dependence of the conductance G has a similar non-monotonic behaviour with a maximum at a temperature comparable with the Thouless energy, while simultaniously Volkov, Allsopp and Lambert [8] predicted that the voltage dependence of the conductance in an S/N mesoscopic structure (Andreev interferometer) has a similar form with a maximum at eV m ≈ ǫ T h . This non-monotonic behaviour has been observed both in very short S/N contacts [9] and in longer mesoscopic S/N structures [10][11][12]21]. In ref [6] it was noted that the conductance δG = G − G n consists of two contributions. The first, δG DOS , is negative due to a proximity effect induced decrease in the density of states (DOS) of the normal wire which makes contact with a superconducting strip [13]. The other contribution δG MT (positive) is analogous to the Maki-Thompson (MT) contribution to the paraconductivity of S/N/S and N/S/N mesoscopic structures and was calculated in [14]. At T = 0 and V = 0 both contributions to the conductance are equal, as T or V increase the contribution δG MT dominates until a maximum is reached, then both these contributions decay.During the past decade a great deal of interest in the transport properties of N/S n...

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Crossover from mesoscopic to classical proximity effects, induced by particle - hole symmetry breaking in Andreev interferometers

Cited by 75 publications

References 41 publications

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

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

Kinetic-equation approach to diffusive superconducting hybrid devices

Anomalous transport in normal-superconducting and ferromagnetic-superconducting nanostructures

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