Regensburg 2000 – scientific programme

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HL: Halbleiterphysik

HL 41: Symposium: Spin-dependent transport in semiconductors - towards a spin transistor

HL 41.5: Fachvortrag

Friday, March 31, 2000, 12:30–12:55, H15

Rashba spin splitting and ferromagnetic electrodes on InAs — •Guido Meier und Dirk Grundler — Universität Hamburg, Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstr. 11, 20355 Hamburg

Controlled transport of spins in low-dimensional electron systems in semiconductors requires to inject a defined spin polarization, to tune it by spin precession at will, and to detect the resulting polarization unambiguously. For the control of the spin polarization inside the semiconductor the gate-voltage dependent spin-orbit interaction (Rashba effect) provides a promising tool. We examine the Rashba effect on p-type single crystals as well as in InAs-based quantum wells. For both systems the Rashba spin splitting parameter α can be tuned up to high values of about 4×10⁻¹¹ eVm at an electron density n_S≈ 1 × 10 ¹² cm⁻². These comparative experiments allow us to distinguish between the contribution due to barrier penetration and built-in electric field, respectively. Ferromagnetic electrodes should provide a high degree of polarization and a low stray field simultaneously. To this end we have prepared permalloy structures on p-type InAs single crystals and measured their magnetization patterns at remanence by magnetic force microscopy. Simulations of the magnetization and hysteresis curve point to their possible use as spin injectors and detectors.