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Magneto-optical spectroscopy of spin injection and spin relaxation in ZnMnSe/ZnCdSe and GaMnN/InGaN spin light-emitting structures

Irina A. Buyanova 1Weimin M. Chen 1Yasuo Oka 2Cammy R. Abernathy 3Stephen J. Pearton 3

1. Linköping University, Dept. of Physics and Meas. Techn., Linkoping, Sweden
2. Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Sendai 980-8577, Japan
3. University of Florida (UF), 227 Chemical Engineering Bldg., Gainesville, FL 32611, United States

Abstract

All-semiconductor spintronics has attracted increasing attention due to its promise to combine new spin enabling functionality with well-established electronic and optical properties that have widely been explored in the present microelectronics and optoelectronics. Among many challenges, efficient spin injection and reliable spin detection are among the key elements required for the success of future semiconductor spintronic devices. In this talk we shall review our recent results from in-depth investigations of physical mechanisms which govern spin injection from spin aligners based on diluted magnetic semiconductors (DMS) and also spin depolarization within non-magnetic spin detectors, by employing cw and time-resolved magneto-optical spectroscopy in combination with tunable laser excitation. Two types of spin-injection structures based on II-VIs (e.g. ZnMnSe/Zn(Cd)Se) and III-Vs (e.g. GaMnN/Ga(In)N) were studied as model cases. We shall show that in ZnMnSe/Zn(Cd)Se two physical mechanisms are responsible for optical spin injection, i.e. (i) commonly believed tunneling of individual carriers or excitons and (ii) energy transfer via localized excitons and spatially separated localized electron-hole pairs (LEHP) located within DMS. Unexpectedly, the latter mechanism is in fact found to dominate spin injections. We shall also show that spin depolarization in the studied structures is largely determined by efficient spin relaxation within non-magnetic spin detectors, which is an important factor limiting efficiency of spin detection. Detailed physical mechanisms leading to efficient spin depolarization will be discussed.

 

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Presentation: Invited oral at E-MRS Fall Meeting 2006, Symposium E, by Irina A. Buyanova
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-12 07:29
Revised:   2009-06-07 00:44