Symmetry-driven large tunneling magnetoresistance in SrRuO3 magnetic tunnel junctions with perpendicular magnetic anisotropy

Magnetic tunnel junctions (MTJs) that are comprised of epitaxially grown complex oxides offer a versatile platform to control the symmetry of tunneling states and tailor magnetic anisotropy useful for practical applications. This work employs thin films of SrTiO3 as an insulating barrier deposited between two ferromagnetic SrRuO3 electrodes to form fully epitaxial MTJs and demonstrate these functionalities. Transport measurements demonstrate large tunneling magnetoresistance (TMR), significantly exceeding previously found values of TMR in MTJs based on SrRuO3 electrodes. These results are explained by perpendicular magnetic anisotropy of SrRuO3 and matching (mismatching) between symmetry and spin across the SrTiO3/SrRuO3 (001) interface for the parallel (antiparallel) MTJ magnetization state, supported by density functional (DFT) calculations. The angular variation of TMR indicates that the SrRuO3 electrodes contain multiple magnetic domains, allowing the devices to exhibit at least three stable resistance states.