Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 19: Spin Dynamics / Spin Torque I

MA 19.10: Vortrag

Mittwoch, 27. Februar 2008, 16:30–16:45, EB 301

Nanowires for high DC current applications — •Sebastian Hankemeier, Konrad Sachse, Yuliya Stark, Matthias Scholz, Germar Hoffmann, Robert Frömter, and Hans Peter Oepen — Universität Hamburg, Germany

For a more detailed investigation of current induced domain wall movement in nanowires by spin torque effect, it is essential to have maximum control of the external experimental parameters, i.e. the current density and the wire temperature. Additional, to study the forces that act on the walls, it is desirable to perform experiments with DC currents large enough to move the domain walls.

In this talk we present the realization of Permalloy nanowires which sustain current densities larger 4 · 10¹² A/m². The wires are made from 20nm thick Permalloy, evaporated on diamond, with a width of 1µm and a length of 25µm. While applying current densities beyond 10¹¹ A/m², we observe ohmic heating of the wires, which causes annealing effects. This effect can be used to improve the specific resistance of the wire near to the values of bulk material. The experiments are performed under HV conditions to prevent oxidation and cooling with liquid nitrogen is necessary for heat dissipation. The temperature of the wire, which depends on the applied current, has been evaluated utilizing the change in wire-resistance and estimated by heat transfer calculations.