Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 26: Spin Dynamics / Spin Torque IV

MA 26.2: Hauptvortrag

Donnerstag, 25. März 2010, 14:30–15:00, H10

Spin dynamics of complex metallic magnets — •Paweł Buczek, Arthur Ernst, and Leonid Sandratskii — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany

Magnons, often termed as spin-waves, are elementary collective excitations of magnets. Every magnon lowers the magnetization of the system by 2µ_B, carries energy and crystal momentum. Their signature is found in the inelastic neutron scattering, spin polarized electron energy loss spectroscopy, inelastic scanning tunneling microscopy and spin-resolved two-photon photoemission experiments. Magnons and other magnetic excitation can be one of the coupling mechanisms in high temperature superconductivity. They control the thermodynamics of magnets. Spintronics approaches limits where the magnetic excitations start to interfere with operation of the devices.

In this theoretical talk we will outline an ab-initio method of studying magnetic excitations based on time dependent density functional theory. The method allows to access both the energies and life times of magnons. We will discuss the applications of the method to half-metallic Heusler compounds. In these materials certain decay channels become inoperative for low-energy spin-waves. Next, we will focus on magnons in thin metallic films, where their properties are strongly influenced by the structure of the films and the presence of substrate. Finally, some attention will be paid to the theoretical interpretation of certain novel experiments capable of probing magnons in nanostructures.