Low resistance and enhanced thermal and electrical stability of the magnetic tunnel junction with a Ti-alloyed Al-oxide barrier

We developed a new Ti-alloyed Al-oxide (TiAlO_x) as an insulating barrier for magnetic tunnel junction (MTJ) that has a lower resistance × area (RA) value and bandgap than when Al-oxide is used. The RA value of the MTJs dropped from 9.5 to 0.69 MΩ μm² as the Ti concentration increased to 5.33 at.%. The lower RA value of the MTJs resulted from the bandgap reduction; the extra bands were composed mainly of Ti-3d orbitals in the bandgap. In addition, a significant tunneling magnetoresistance (TMR) value of 20% was maintained after annealing at 450°C and a higher bias voltage (V_h) and breakdown voltage (V_B) of 681 mV and 1.35 V, respectively, were obtained in the MTJs with a 5.33 at.% TiAlO_x barrier. These results were closely related to the enhanced microstructural and interfacial quality of the Ti-Al alloy film in the preoxidation state.