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MA: Fachverband Magnetismus

MA 22: Spin Dynamics / Spin Torque III

MA 22.6: Vortrag

Donnerstag, 25. März 2010, 11:00–11:15, H10

Local spin-transfer torque within narrow domain walls — •Stellan Bohlens and Daniela Pfannkuche — I. Institut für Theoretische Physik

In mesoscopic ferromagnets, a domain structure that consists of regions in which the magnetization points in different spatial directions is energetically more favorable than a monodomain. The individual domains are separated by domain walls, where the magnetization changes continuously. A current traversing such a non-collinear magnetization texture exerts a spin-transfer torque on the local magnetization. A consistent theory of spin-transfer torque and spin transport that is also applicable for narrow domain walls is still missing and its impacts are not assessable to date.

We present a theoretical formulation of electron and spin transport that allows for the derivation of the local spin-transfer torque in general magnetization textures. The framework provides the microscopic derivation of transport coefficients that were treated so far as phenomenological parameters in the theory of the spin-transfer torque. [1] We apply our formalism to a Bloch wall and calculate the spatially resolved spin-transfer torque. In the case of narrow domain walls it turns out that the treatment of coupled charge and spin transport offers startling insight into fascinating physics in an intermediate transport regime that comprises diffusive charge transport and ballistic spin transport at the same time.

[1] S. Zhang and Z. Li, Phys. Rev. Lett. 93, 127204 2004