PUB - Publikationen an der Universität Bielefeld

The ferrimagnetic Heusler compound Mn2VGa is predicted to have a pseudogap inthe majority spin channel, which should lead to a negative tunnelmagnetoresistance. We synthesized epitaxial Mn2VGa thin films on MgO(001)substrates by dc and rf magnetron co-sputtering, resulting in nearlystoichiometric films. XRD analysis revealed a mostly B2-ordered structure forthe films deposited at substrate temperatures of 350{\deg}C, 450{\deg}C, and550{\deg}C. Magnetic tunnel junctions with MgO barrier and CoFecounter-electrodes were fabricated. After post-annealing at up toT_a=425{\deg}C negative TMR was obtained around zero bias, providing evidencefor the inverted spin-polarization. Band structures of both electrodes werecomputed within the coherent potential approximation and used to calculate theTMR(V) characteristics, which are in good agreement with our experimentalfindings.