Regensburg 2016 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 14: Spintronics: Transport and Theory

HL 14.3: Talk

Monday, March 7, 2016, 15:15–15:30, H13

Spin injection devices with a two-dimensional electron gas channel in an (Al,Ga)As/GaAs heterostructure — •Thomas Kuczmik, Dino Popp, Martin Oltscher, Josef Loher, Dieter Schuh, Dominique Bougeard, Mariusz Ciorga, and Dieter Weiss — Universität Regensburg

In recent years spin injection phenomena in bulk semiconductors have been extensively studied. However, many spintronic device concepts, like the Datta-Das spin FET, require spin transport in a two-dimensional electron gas (2DEG).

We have recently demonstrated efficient spin injection into a high mobility 2DEG confined in an inverted (Al,Ga)As/GaAs heterostructure, using (Ga,Mn)As/GaAs Esaki diodes as spin selective contacts [2]. In this contribution we discuss some issues related to the design of the employed heterostructure and to sample fabrication that are critical to preparation of working spin injection devices with a 2D channel. Particular attention has to be devoted to avoiding a parasitic 3D-like conduction channel that can be parallel to the 2DEG channel and therefore can compromise spin transport in the latter. Such a parallel channel can be formed below the active channel, on the (Al,Ga)As side of the heterojunction, in the region of the delta-doping by illuminating the device. We compare the results of nonlocal spin valve measurements on samples with and without any parasitic channel and discuss in details how the presence of such a channel affects the measured spin signal.

[1] M. Oltscher et al., Phys. Rev. Lett. 113, 236602 (2014).