Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance

Christoph Klewe; Markus Meinert; Jan Schmalhorst; Günter Reiss

doi:10.1088/0953-8984/25/7/076001

Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance

Materials Science 2013-01-31 v1

Authors: 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{\deg}C, 450{\deg}C, and 550{\deg}C. Magnetic tunnel junctions with MgO barrier and CoFe counter-electrodes were fabricated. After post-annealing at up to T_a=425{\deg}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.

Keywords

magnetic tunnel junction spin polarization heusler compound tunnel magnetoresistance mn2vga b2 ordering coherent potential approximation

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@article{arxiv.1210.2966,
  title  = {Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance},
  author = {Christoph Klewe and Markus Meinert and Jan Schmalhorst and Günter Reiss},
  journal= {arXiv preprint arXiv:1210.2966},
  year   = {2013}
}

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12 pages, 6 figures

Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance

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