Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 24: FV Internal Symposium in honour of Nobelprice 2007 to Peter Grünberg and Albert Fert

MA 24.2: Hauptvortrag

Donnerstag, 28. Februar 2008, 10:00–10:30, EB 301

From giant magnetoresistance to current-induced magnetic switching: theoretical aspects — •Jozef Barnas — Department of Physics, Adam Mickiewicz University, Poznań, Poland

The presence of two well-defined and strongly spin-dependent transport channels in ferromagnetic metals leads to the phenomenon of giant magnetoresistance (GMR) in magnetic layered structures. The discovery and successful applications of GMR led to a new branch of mesoscopic electronics, called spin electronics or briefly spintronics. Some basic theoretical aspects related to the GMR in magnetic multilayers as well as those related to semiconductor and molecular spintronics will be briefly discussed. Another consequence of the presence of two spin channels for electronic transport (and also of the discovery of GMR) is the phenomenon of current-induced magnetic switching (CIMS) due to spin torque. The latter is a consequence of spin transfer from conduction electrons to local magnetic moments. The spin torque can generate transitions between different local (quasi)equilibrium states. At some conditions, however, the spin-transfer torque may cause transition to dynamical states of microwave frequency, where the energy is pumped from a voltage source to the magnetic system. Of particular interest are structures, in which the microwave precessional states can be induced in the absence of external magnetic field.