Effects of ferroelectricity and magnetism on electron and spin transport in Fe/BaTiO3/Fe multiferroic tunnel junctions

First principles electronic structure and transport calculations are used to demonstrate the impact of the electric polarization on electron and spin transport in Fe/BaTiO3/Fe multiferroic tunnel junctions (MFTJs). We find that the polarization of BaTiO3 reduces the tunneling conductance, as compared to a nonpolarized barrier, due to the change in the electronic structure driven by ferroelectric displacements, similar to that found previously for Pt/BaTiO3/Pt. For the MFTJ, however, this effect has different magnitudes for majority- and minority-spin channels and for parallel and antiparallel orientations of the magnetization of the electrodes. As a result, we find a substantial drop in the spin polarization of the tunneling current in the parallel configuration and an inversion of the magnetoresistance as polarization of the barrier is turned on. (c) 2008 American Institute of Physics.