Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 78: Invited Talk Mariusz Ciorga

HL 78.1: Hauptvortrag

Donnerstag, 19. März 2015, 12:30–13:00, ER 164

Electrical spin injection into high mobility 2DEG systems — Martin Oltscher, •Mariusz Ciorga, Josef Loher, Dieter Schuh, Dominique Bougeard, and Dieter Weiss — Institute for Experimental and Applied Physics, University of Regensburg

Effective spin injection into two-dimensional (2D) electron systems is a prerequisite for many new functionalities in future devices, with a Datta-Das spin field effect transistor [1] being a primary example. Whereas real progress in understanding of spin injection phenomena in bulk semiconductors has been achieved, electrical injection of spins into high mobility 2D systems remains a relatively open matter.

Here I present the results of our recent experiments [2] on electrical spin injection into high mobility 2D electron gas (2DEG) confined in an inverted AlGaAs/GaAs heterojunction, with ferromagnetic semiconductor (Ga,Mn)As employed as a spin polarizing material. We observed a clear nonlocal spin signal that could be tuned by a voltage applied across the injector. At maximum the signal largely exceeded the prediction of the standard drift-diffusion model. A strong correlation of this enhancement with the width of the contacts and with the electrons’ mean free path led us to the conclusion that ballistic nature of the transport in the 2D region directly below the injector should be considered to fully describe the experimental outcome.

The work has been supported by Deutsche Forschungsgemeinschaft (DFG) through SFB689.

[1] S. Datta and B. Das, Appl. Phys. Lett. 56, 665 (1990) [2] M. Oltscher et al., Phys. Rev. Lett. 113, 236602 (2014)