Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 31: Focus Session: Magnetic Damping Phenomena in Thin Films and Nanostructures
(jointly with DS)

MA 31.1: Topical Talk

Mittwoch, 13. März 2013, 15:00–15:30, H10

An overview of magnetic damping in ferromagnets — •Robert McMichael — National Institute of Standards and Technology, Center for Nanoscale Science and Technology, Gaithersburg MD USA

Many of the applications for magnetic nanotechnology depend on the ability to write and read information quickly by switching and measuring the magnetization in magnetic nanostructures, and the magnetic damping plays an important role in the dynamics. The desired amount of damping depends on the application. For example, in some cases, strong damping enables fast switching, while in other cases strong damping prevents switching. In this talk, I will give a brief introduction to the phenomenology of damping, or relaxation, of magnetization in ferromagnets, which is often nicely described by a viscous drag or Gilbert damping. I aim to supplement this phenomenological picture by reviewing the current understanding of damping mechanisms in ferromagnetic metals. The primary mechanism involves transferring energy to electronic states near the Fermi surface. Additionally, in nanostructures, the dynamic effects of damping can be modified by spin polarized currents either that are injected from external sources or that are generated spontaneously by the magnetization precession. I will conclude by focusing on problems of interpreting damping measurements in materials with defects, and on the opportunities for intrinsic damping measurements in nanostructures.