Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 23: Nanoelektronik II: Spin-Elektronik

TT 23.2: Vortrag

Mittwoch, 10. März 2004, 17:45–18:00, H19

Persistent spin currents in mesoscopic Heisenberg rings — •Florian Schütz, Marcus Kollar, and Peter Kopietz — Institut für Theoretische Physik, Universität Frankfurt, Robert-Mayer-Str. 8, 60054 Frankfurt/Main

We discuss spin transport in magnetic insulators and show that a spatially inhomogeneous magnetic field gives rise to a persistent spin current around a mesoscopic Heisenberg ring [1]. This is a mesoscopic quantum interference effect and is analogous to persistent charge currents in normal metal rings threaded by a magnetic flux. The spin current is carried by magnons and is driven by a geometric flux. For a ferromagnetic ring spin waves are thermally activated while for an antiferromagnetic ring quantum fluctuations lead to a magnetization current even in the ground state. Since moving magnetic dipoles produce electric fields, the magnetization current leads to an electric dipole moment perpendicular to the ring plane, which may allow the experimental detection of this effect.

[1] F. Schütz, M. Kollar, and P. Kopietz, Phys. Rev. Lett. 91, 017205 (2003); cond-mat/0308230.