Regensburg 2002 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 12: Niedrigdimensionale Systeme, Magnetotransport II
TT 12.3: Vortrag
Dienstag, 12. März 2002, 15:30–15:45, H18
Spin-dependent magnetoconductance in ballistic microstructures — •Diego Frustaglia1, Martina Hentschel1, and Klaus Richter2 — 1Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden — 2Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg
We study spin-dependent electronic transport through mesoscopic rings in the presence of non-uniform magnetic fields. Both one and two dimensional systems are studied using a transfer matrix and recursive Green’s function approach, respectively. Ahronov-Bohm oscillations in the magnetoconductance arise due to the electromagnetic coupling to the electron’s charge. Moreover, the magnetic coupling to the electronic spin causes additional effects. In the limit of adiabatic spin transport (in strong magnetic fields) the appearance of Berry phases has been predicted. For general non-uniform magnetic fields we follow the average transmission from the diabatic to the adiabatic limit by increasing magnetic field strength. We focus on the appearance of signatures of geometric phases and find general agreement between the results of one and two dimensional calculations. In particular, for in-plane magnetic fields, the adiabatic regime with zero transmission due to Berry phases is approached by a Lorentzian decay with additional structures that can be understood within the one-dimensional model.