  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.
