Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Spin-Dynamics / Spin-Torque IV

MA 35.6: Vortrag

Donnerstag, 26. März 2009, 16:30–16:45, HSZ 04

Ab-initio calculations on the Elliott-Yafet mechanism for the discussion of femtosecond magnetization dynamics — •Daniel Steiauf and Manfred Fähnle — Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart

Ultrashort laser pulses are able to reduce the magnetization of ferromagnetic metals such as Ni. Thereby, angular momentum is transferred from the spin system faster than a picosecond, however, not into the electronic orbital moments, as shown by recent experiments. Thus the lattice has to be involved. The Elliott-Yafet [1,2] mechanism, a spin-orbit mediated spin-flip scattering of an electron at a phonon, is one possible, however questioned, candidate to explain the ultrafast demagnetization after fs laser excitation. The doubts have arisen as the value of the Elliott-Yafet spin-mixing parameter of Ni has not been known and has been assumed to be similar to the one of Cu which is very small. We present ab-initio calculations of the spin-mixing within the density functional electron theory for various alkali, transition and rare earth metals. The spin mixing of the electronic system is induced by spin-orbit coupling as well, and is a measure for the strength of the spin-flip scattering.

[1] R. J. Elliott, Phys. Rev. 96, 266 (1954).

[2] Y. Yafet, in “Solid State Physics”, F. Seitz and D. Turnbull (eds.) (Academic, New York, 1963), Vol. 14