Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance

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.

arXiv comment12 pages, 6 figures

References in corpus (7)

• Slater-Pauling Behavior of the Half-Ferromagnetic Full-Heusler Alloys
• Half-Metallic Ferrimagnetism in Mn_2VAl
• Search for half-metallic ferrimagnetism in V-based Heusler alloys Mn${}_2$VZ (Z$=$Al, Ga, In, Si, Ge, Sn)
• Analysis of L21-ordering in full-Heusler Co2FeSi alloy thin films formed by rapid thermal annealing
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• Ferrimagnetism and disorder in epitaxial Mn(2-x)Co(x)VAl thin films
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Cited by in corpus (2)

• Sign change in the tunnel magnetoresistance of Fe3O4/MgO/Co-Fe-B magnetic tunnel junctions depending on the annealing temperature and the interface treatment
• Tunnel magneto-Seebeck effect