Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 23: Nanoelectronics II - Spintronics and Magnetotransport

TT 23.9: Vortrag

Donnerstag, 29. März 2007, 11:45–12:00, H19

Universality in Voltage-driven Nonequilibrium Phase Transitions — •Michael Arnold and Johann Kroha — Physikalisches Institut, Nussallee 12, 53115 Bonn

We consider the non-equilibrium ferromagnetic transition of a mesoscopic sample of a resistive Stoner ferromagnet coupled to two paramagnetic leads. The transition is controlled by either the lead temperature T or the transport voltage V applied between the leads. We calculate the temperature and voltage dependence of the magnetization. In the particle hole symmetric case we find within mean-field theory that even at finite bias the magnetization does not depend on the position along the sample axis, although the charge density and other quantities do vary. This may be relevant for possible spintronics applications. In addition, we establish a generalized control parameter in terms of T and V which allows for a universal description of the temperature- and voltage-driven transition.