Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 22: Internal Symposium “50 Years AG Magnetism”

MA 22.4: Hauptvortrag

Mittwoch, 29. März 2006, 17:00–17:30, HSZ 03

Spin transfer phenomena in layered magnetic structures — •Peter A. Grünberg, Daniel E. Bürgler, and Claus M. Schneider — FZ-Jülich, IFF

The discovery of interlayer exchange coupling (IEC) in 1986 was followed in 1988 by the first detection of No-dqGiant MagnetoresistanceNo-dq (GMR) and in 1995 by a rediscovery of tunnel magnetoresistance (TMR). Finally after its theoretical prediction in 1995, in 1999 there was the first experimental observation of current induced magnetic switching (CIMS). All mentioned phenomena rely on the transfer of electron spin between neighbouring magnetic layers across nonmagnetic interlayers in layered magnetic structures. Here we want to give an overview of this worldwide activity.

The phenomena can be classified according to the nature of the interlayer material used: metallic, semiconducting, insulating. Generally IEC is only obtained across metallic interlayers, but there are exceptions like IEC of Fe across Si and MgO. Furthermore IEC across well ordered Si turns out to be surprisingly strong. Likewise TMR is expected and indeed observed across semiconductors and insulators but so far could not be detected across Si, despite many efforts due to technical relevance. On the other hand values as big as a few hundred percent have been observed for TMR across MgO, in agreement with a theoretical prediction. We shall present and discuss the mentioned phenomena in the framework of associated band structures, where emphasis will be given to a basic physical understanding. Already existing and possible future applications will also be considered.