Regensburg 2002 – wissenschaftliches Programm

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MA: Magnetismus

MA 6: Spinabhängige Transportphänomene I

MA 6.5: Vortrag

Montag, 11. März 2002, 16:15–16:30, H22

Spin-dependent Quantum Transport: Criterion for Adiabaticity in Disordered Mesoscopic Systems — •Markus Popp¹, Diego Frustaglia², and Klaus Richter¹ — ¹Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg — ²MPI für Physik Komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden

We consider spin-dependent quantum transport in mesoscopic systems with inhomogeneous magnetic fields. If the electron spin couples adiabatically to the spatially varying field, the spin wave function acquires a geometrical or Berry phase that gives rise to effects on the ballistic magnetoconductance[1]. Using a recursive Green’s function method we calculate transmission probabilities for different mesoscopic structures and address the problem how the adiabatic regime is reached in the presence of impurities. Our numerical results provide an answer to the controversial discussion[2,3], whether the elastic scattering time or the Thouless time sets the relevant time scale for adiabaticity in disordered samples.

[1] A. Stern, Phys. Rev. Lett. 68, 1022 (1992);

  D. Frustaglia and K. Richter, Found. of Physics 31, 399 (2001).

[2] S.A van Langen, H.P.A. Knops, J.C.J. Paasschens,

  C.W.J. Beenaker, Phys. Rev. B 59, 2102 (1999).

[3] D. Loss, H. Schöller, P. Goldbart, Phys. Rev. B 59, 13328 (1999);

  H. A. Engel and D. Loss, Phys. Rev. B 62, 10238 (2000)