Voltage-induced perpendicular magnetic anisotropy change in magnetic tunnel junctions

A voltage-induced perpendicular magnetic anisotropy change in an ultrathin FeCo layer was observed in an epitaxial magnetic tunnel junction (MTJ) structure. A spin-transfer induced ferromagnetic resonance measurement technique was used under various bias voltage applications to evaluate the anisotropy change. From the peak frequency shifts, we could estimate that a surface magnetic anisotropy change of 15 mu J/m(2) was induced by an electric field application of 400 mV/nm in the MTJ with a 0.5 nm thick FeCo layer. The realization of voltage-induced anisotropy changes in an MTJ structure should have a large impact on the development of electric-field driven spintronic devices.