Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 23: Posters Superconductivity, Solids at Low Temperature

TT 23.50: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU D

Fractional thermal magnetoconductance of one-dimensional proximity systems — •Grigory Tkachov — Institute for Theoretical Physics, Regensburg University, 93040 Regensburg, Germany

While phase-coherent charge transport in mesoscopic normal metal/superconductor systems has been receiving considerable attention, heat conduction properties of such proximity structures have been explored to a much lesser extent (see, e.g. Refs. [1,2]). The purpose of this talk is to present a theoretical study of anomalous magnetic field behaviour of heat transport in quasi-one-dimensional ballistic wires coupled in parallel to superconductors [3,4]. The proximity effect is described in terms of Andreev bound states whose spectrum acquires a minigap due to the mixing of particle and hole states in the wire. In the presence of a magnetic field B, a specific interplay between the Zeeman spin splitting and the effect of a proximity-induced screening supercurrent is found to preserve time-reversal symmetry for certain groups of Andreev states with the minigap independent (or weakly dependent) of B. In this regime the low-temperature thermal magnetoconductance of the wire is predicted to increase in portions equal to half of the thermal conductance quantum.

[1] J. Eom, C.-J. Chien, and V. Chandrasekhar, Phys. Rev. Lett. 81 437 (1998); A. Parsons, I. A. Sosnin, and V. T. Petrashov, Phys. Rev. B 67 140502 (2003).

[2] E. V. Bezuglyi and V. Vinokur, Phys. Rev. Lett. 91 137002 (2003).

[3] G. Tkachov, to appear in Physica C (2005);cond-mat/0402158.

[4] G. Tkachov and V. I. Fal’ko, Phys. Rev. B 69 092503 (2004).