Spin relaxation and spin coherence in nonmagnetic metallic ultrathin films and nanowires.

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In the field of spintronics, there is a vision of information transfer by spin-polarized currents through non-magnetic materials. In any material, however, dissipation of spin currents leads to spin relaxation and loss of information. The corresponding spin relaxation rate depends on intrinsic and extrinsic factors, such as point defects, crystal surfaces, lattice vibrations, etc., which all together contribute to spin-flip scattering via the effect of spin-orbit coupling (SOC). We aim at an understanding and quantitative prediction of these phenomena, with special focus on thin and ultra-thin metallic films that are commonly used in experimental spintronics devices, but also in nanowires where the reduced dimensionality can lead to surprising new physics. We wish to understand how spin relaxation is affected by the sample-dependent electronic structure, such as surface states, scattering at the substrate, or impurities that occur during sample preparation. We want to compare the effect of scattering at point defects to that of phonons, and to see if the Elliott-Yafet type of relaxation is dominant, or if the Dyakonov- Perel mechanism for spin decoherence can be also important. Finally we want to see if the reduced dimensionality can partly suppress spin relaxation even in the presence of strong spin-orbit coupling, in view of the importance of the latter for the spin-Hall effect.