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arXiv · 1210.2966

Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance

Christoph Klewe·Markus Meinert·Jan Schmalhorst·Günter Reiss
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Abstract

The ferrimagnetic Heusler compound Mn2VGa is predicted to have a pseudogap in the majority spin channel, which should lead to a negative tunnel magnetoresistance. We synthesized epitaxial Mn2VGa thin films on MgO(001) substrates by dc and rf magnetron co-sputtering, resulting in nearly stoichiometric films. XRD analysis revealed a mostly B2-ordered structure for the films deposited at substrate temperatures of 350°C, 450°C, and 550°C. Magnetic tunnel junctions with MgO barrier and CoFe counter-electrodes were fabricated. After post-annealing at up to T_a=425°C negative TMR was obtained around zero bias, providing evidence for the inverted spin-polarization. Band structures of both electrodes were computed within the coherent potential approximation and used to calculate the TMR(V) characteristics, which are in good agreement with our experimental findings.

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Christoph Klewe, Markus Meinert, Jan Schmalhorst, Günter Reiss. 2012-10-10. Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance. https://doi.org/10.1088/0953-8984%2F25%2F7%2F076001

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