Regensburg 2000 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 17: Postersitzung II: Pinning und Vortexdynamik (1-8), Supraleitung: Theorie (9-13), Korrelierte Elektronen (14-48), Niederdimensionale Systeme (49-68), Quantenflüssigkeiten (69-75)

TT 17.65: Poster

Mittwoch, 29. März 2000, 14:30–18:00, A

Signatures of Non-Uniform Magnetic Fields in Quantum Transport: Geometrical Phases — •Diego Frustaglia, Martina Hentschel, and Klaus Richter — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, D-01187 Dresden, Germany

We study electronic quantum transport through ballistic mesoscopic one- and two-dimensional rings in the presence of a micromagnet as a function of an external homogeneous magnetic field. The 2D-systems are studied numerically by means of a recursive computation of the Green’s function on the basis of Dyson’s equation in a tight-binding model. We compare the diagonal-channel contribution to the reflection coefficient with semiclassical calculations in order to analyze the influence of pairs of time reversed paths. Geometrical-phase effects due to spin-coupling to the non-uniform magnetic field [1,2] are explored for single as well as ensemble-averaged structures, giving rise to modifications in the Aharonov-Bohm-like oscillations patterns. We also present a corresponding semiclassical approach and implications for related experiments are discussed.

[1] M.V. Berry, Proc. R. Soc. London A 392, 45 (1984).

[2] A. Stern, Phys. Rev. Lett. 68, 1022 (1992); S.A. van Langen, H.P.A. Knops, J.C.J. Paasschens and C.W.J. Beenakker, Phys. Rev. B 59, 2012 (1999); D. Loss, H. Schoeller and P.M. Goldbart., Phys. Rev. B 59, 13328 (1999).