Berlin 2012 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 4: Spin-dependent Transport Phenomena
MA 4.13: Vortrag
Montag, 26. März 2012, 12:45–13:00, H 1012
Ab initio investigation of the Elliott-Yafet parameter in symmetric ultrathin W films — •N. H. Long, P. Mavropoulos, S. Heers, B. Zimmermann, Y. Mokrousov, and S. Blügel — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
The spin relaxation in non-magnetic metallic thin films is an important effect in spintronics [1]. In systems with space-inversion symmetry, the spin relaxation is mainly due to the Elliott-Yafet mechanism [2,3]: momentum scattering (|k⟩→|k′⟩) at impurities or phonons can cause spin-flip scattering due to the presence of spin-orbit coupling of degenerate Bloch states, that entails a k-dependent superposition of spin-up and -down states. Within this model, momentum- and spin-relaxation rate are proportional. The proportionality factor is the Elliott-Yafet parameter b2, which quantifies the degree of admixture of states with different spin character in a crystal. In this work, we calculate the b2 parameter of symmetric W(100) and W(110) ultrathin films using the Korringa-Kohn-Rostoker Green function method. Our results reveal an oscillation of the b2 parameter as a function of thickness of the films, as well as a significant anisotropy. We discuss our findings in terms of the symmetry properties of bulk and surface states on the Fermi surface of the films. We acknowledge funding from DFG under MO 1731/3-1 and HGF-YIG Programme VH-NG-513.
[1] I. Žutić, J. Fabian, S. Das Sarma, Rev. Mod. Phys. 76, 323 (2004).
[2] R. J. Elliott, Phys. Rev. 96, 266 (1954).
[3] Y. Yafet, Solid State Physics, Vol. 14, 2 (1963).