Magnetic tunnel junctions with a rock-salt-type Mg1−xTixO barrier for low resistance area product

Ti-doped MgO (MTO) barriers were examined for polycrystalline magnetic tunnel junctions (MTJs) in combination with CoFeB ferromagnetic electrodes. The high tunneling magnetoresistance (TMR) ratio up to 240% and 160% was observed for the MTJs with Mg0.95Ti0.05O and Mg0.9Ti0.1O barriers after annealing at 450 °C. This high TMR ratio implies the presence of coherent tunneling. For a given thickness, MTJs with the MTO barriers were confirmed to have lower resistance-area product (RA) compared to those with the MgO barriers, suggesting the intrinsically lower barrier height of the MTO barriers. The MTO-based MTJs exhibit higher TMR ratio than those of the MgO-based MTJs for the RA range lower than 5 Ω μm2 as a consequence of thicker barriers and better wettability. This work has demonstrated the potential of the MTO barriers for low-RA MTJs.