Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 41: Spinabh
ängiger Transport II
HL 41.2: Vortrag
Donnerstag, 11. März 2004, 15:30–15:45, H17
Anomalous Spin Dephasing in (110) GaAs Quantum Wells — •Daniel Hägele1, Stefanie Döhrmann1, Jörg Rudolph1, Dieter Schuh2, and Michael Oestreich1 — 1Universität Hannover, Institut für Festkörperphysik, Abteilung Nanostrukturen, Appelstr. 2, D-30167 Hannover — 2Walter Schottky Institut, Technische Universität München, Am Coulombwall, D-85748 Garching
GaAs quantum wells grown on (110) oriented substrates are considered prime candidates for room temperature spintronics. The electron spin lifetime in such structures had recently been demonstrated to exceeded the lifetime found in (100) grown quantum wells by about an order of magnitude [1]. However, we observe a strong anisotropy of electron spin decoherence in n-doped (110) GaAs/(AlGa)As quantum wells. We measure long lifetimes for electron spin along (110) direction, but the lifetime for spin perpendicular to (110) is dramatically reduced by up to a factor of ten, which has direct implications for the design of spintronic devices. We also observe that spin lifetimes decrease monotonically for both spin orientations above a temperature of 80 and 120 K, respectively. In case of (110) spin orientation the decrease is very surprising and cannot be explained with the usual Dyakonov Perel dephasing mechanism. A novel spin dephasing mechanism is put forward based on scattering of electrons between different quantum well subbands.
[1] Y. Ohno et al., Phys. Rev. Lett. 83, 4196 (1999)