Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 92: Spintronics II (with MA/O/TT)

HL 92.9: Talk

Thursday, April 3, 2014, 12:00–12:15, POT 151

Spin injection efficiency dependence on MgO tunnel barrier thickness — •Lennart-Knud Liefeith, Tomotsugu Ishikura, Zhixin Cui, and Kanji Yoh — Research Center for Integrated Quantum Electronics, Japan

We study non-local spin valves in inverted InAlAs/InGaAs high-electron mobility transistors on InP(001). On the ferromagnet (FM) side, permalloy electrodes are employed. On the semiconductor (SC) side the electron system resides in a two-dimensional InAs channel. It has been argued that direct FM/SC contacts provide negligible spin polarization in the SC if the transport is diffusive, known as the conductivity mismatch problem[1]. In the ballistic transport regime efficient spin injection is predicted[2]. For devices basing on ballistic transport, a low contact resistance between FM and SC is essential. An strategy to tackle the conductivity mismatch problem is the insertion of a tunnel barrier at the FM/SC interface. We thus study ballistic structures with MgO tunnel barriers of varied thickness. Here we will compare spin injection efficiencies in non-local spin valve structures with either no or a 2 nm-thick MgO tunnel barrier at the FM/SC interface.
[1] G. Schmidt, Fundamental obstacle for electrical spin injection from a ferromagnetic metal into a diffusive semiconductor, Physical Review B 62, R4790 (2000)
[2] M. Zwierzycki, Spin-injection through an Fe/InAs interface, Physica Status Solidi A: Applications and Materials Science 1, 25-28 (2003)