Regensburg 2007 – wissenschaftliches Programm

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SYSS: Symposium Spins in Semiconductors

SYSS 1: Spins in Semiconductors

SYSS 1.5: Hauptvortrag

Montag, 26. März 2007, 11:00–11:20, H1

Electrical spin injection and detection in semiconductors — •Paul Crowell — University of Minnesota, Minneapolis MN , USA

In the last several years, there has been substantial progress in achieving efficient electrical spin injection from ferromagnetic metals into semiconductors. In contrast, electrical spin detection has been a more significant obstacle. I will discuss recent experiments that have addressed this difficulty, leading to a definitive demonstration of electrical spin injection and detection in lateral Fe/GaAs/Fe devices [1]. Our measurements are carried out in a non-local geometry in which the spin-dependent electrochemical potential at the detector is measured when the magnetizations of the Fe source and detection electrodes are either parallel or antiparallel. Precession and dephasing of the electron spin polarization in a transverse magnetic field are confirmed by observation of a Hanle effect in the non-local voltage. The dependence of the non-local signal on transverse magnetic field, contact separation, and temperature are in good agreement with a spin drift-diffusion model. A non-local voltage due to spin accumulation is also observed when the source electrode is under forward bias. The bias dependence of the non-local voltage, which can be compared directly with optical measurements of the spin polarization, will be discussed.

This work was carried out in collaboration with X. Lou, C. Adelmann, S.A. Crooker,E. S. Garlid, J. Zhang, S.M. Reddy, S.D. Flexner, and C.J. Palmstrøm and was supported by ONR and NSF.

[1] X. Lou et al., cond-mat/0701021