Regensburg 2013 – scientific programme
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MA: Fachverband Magnetismus
MA 12: Focus Session: Terahertz Spintronics
MA 12.5: Topical Talk
Tuesday, March 12, 2013, 11:30–12:00, H10
Ultra-fast spin currents in transparent magnetic tunnel junctions — •Andy Thomas — Universität Bielefeld, Universitätsstrasse 25, 33615 Bielefeld
Ultra-fast spin current can also be excited in magnetic tunnel junctions (MTJs). We prepared MTJs with tunnel magnetoresistance (TMR) ratios of up to 320% at room temperature with 2.4 nm magnesia tunnel barriers. Current induced magnetic switching (3× 106 A/cm2) was observed for MTJs with 1.1 nm MgO barrier while maintaining a TMR ratio of 100%. We further reduced the barrier thickness and we were able to achieve 60% TMR ratio for 3 ML ultra-transparent MgO tunnel barriers. In these junctions, low switching currents can be realized. Furthermore, currents can be generated using a femtosecond laser and temperature gradients of 10 K/nm are possible across the tunnel barrier. These ultra-fast pulses generate spin-polarized charge current bunches which can be modified via the TMR effect of the junctions.
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[2] M. Walter et al., Nature Mater. 10 (2011) 742
[3] G. M. Müller et al., Nature Mater. 8 (2009) 56