Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 6: TR: Nanoelectronics II: Spintronics and Magnetotransport

TT 6.9: Talk

Monday, March 22, 2010, 16:15–16:30, H19

Spin accumulation with spin-orbit interaction — •Henri Saarikoski^1,2,3 and Gerrit E. W. Bauer¹ — ¹Kavli Institute of Nanoscience, Delft University of Technology, 2628-CJ Delft, The Netherlands — ²Mathematical Physics, Lund Institute of Technology, SE-22100 Lund, Sweden — ³Present address: University of Regensburg, 93040 Regensburg

Spin accumulation is a crucial but imprecise concept in spintronics. In metal-based spintronics it is characterized in terms of semiclassical distribution functions. In semiconductors with a strong spin-orbit coupling the spin accumulation is interpreted as a superposition of coherent eigenstates. We show that both views can be reconciled by taking into account the electron-electron interaction: a sufficiently strong self-consistent exchange field reduces a spin accumulation to a chemical potential difference between the two spin bands even in the presence of spin-orbit coupling. We demonstrate the idea on a clean two-dimensional electron gas (2DEG) by showing how the exchange field protects a spin accumulation from dephasing and introduces an easy-plane anisotropy. Spin can be injected either adiabatically, e.g. by a ferromagnetic contact with small electric bias, or diabatically, e.g. by pulsed optically induced excitation. We discuss spin-accumulation eigenstates that are accessible by adiabatic excitation as well as spin accumulation dynamics of rapidly excited states. We illustrate the general ideas at the hand of a 2DEGs with Rashba SOI, in which the disorder-scattering lifetime broadening is much smaller than the spin-orbit splitting at the Fermi-level.