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PGI-1 Seminar: Dr. Henri Jaffres

Electrical detection of spin accumulation in conductive channel probed by electrical Hanle effects and spin pumping experiments

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31.May.2012 11:30
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PGI-Hörsaal

Unité Mixte de Physique CNRS/Thales, Palaiseau, France

Abstract

In this seminar, we will show how electrical Hanle experiments appear like an efficient method to detect the levelof spin accumulation in a conductive channel (GaAs, Si...) generated by current injection beneath a magnetic tunnelinjector. In particular, we will present experimental data obtained on Co/Al2O3/GaAs and CoFe/MgO/Ge systemsshowing how, in such semiconductor systems, a preferential tunneling spin injection into interfacial electronic states canenhance both spin accumulation and electrical Hanle signal by confinement effects also limiting the efficiency of spininjection into the conduction band itself (at least at low bias and at low temperature). In the case of Ge, an efficient spininjection into the conduction band, probed either by the action of a back-gate or by ferromagnetic resonance (FMR)through 'spin pumping' effects, is recovered at a temperature sufficiently high to untrap the carriers from the localizedcenters (typically above 200 K). In the end, we will present our very recent experiments concerning a first-step towardselectrical spin injection in oxyde LaAlO3/SrTiO3 systems probed by the same electrical Hanle technique.

Contact

Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Fax: +49 2461 61-2850
email: s.bluegel@fz-juelich.de

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