  Perpendicular magnetic tunnel junction with MgAl2O4 barrier is investigated.
It is found that reactive RF sputtering with O2 is essential to obtain strong
perpendicular magnetic anisotropy and large tunneling magnetoresistance in
MgAl2O4-based junctions. An interfacial perpendicular magnetic anisotropy
energy density of 2.25 mJ/m2 is obtained for the samples annealed at 400C. An
enhanced magnetoresistance of 60% has also been achieved. The Vhalf, bias
voltage at which tunneling magnetoresistance drops to half of the zero-bias
value, is found to be about 1V, which is substantially higher than that of
MgO-based junctions.
