Regensburg 2004 – scientific programme

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MA: Magnetismus

MA 16: Magn. Kopplungsph
änomene

MA 16.1: Talk

Wednesday, March 10, 2004, 15:15–15:30, H22

Temperature Dependence of Interlayer Exchange Coupling — •Stephan Schwieger and Wolfgang Nolting — Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr.15, 12489 Berlin

The coupling of two magnetic layers (e.g. Co,Ni) seperated by a nonmagnetic spacer (e.g.Cu) is well understood in terms of the quantum interference model as e.g. proposed by P. Bruno.

The dominant contribution to it’s temperature dependence is less certain. Two mechanisms that are discussed are the softening of the Fermi surface within the spacer and the interaction of spin wave excitations within the magnetic material.

Here another mechanism is proposed, that is based on the strong temperature dependence of thermodynamic potentials as the free energy. This reflects the fact, that expectation values like ⟨S_iaS_ib⟩ , where S_ia and S_ib indicate spins in different magnetic layers, are strongly temperature dependent compared to excitations like spin waves or the softening of the Fermi surface.

This approach is evaluated within the Heisenberg model and compared to FMR experiments.