Voltage-Induced Magnetic Anisotropy Changes in an Ultrathin FeB Layer Sandwiched between Two MgO Layers

We investigated the effect of voltage on the perpendicular magnetic anisotropy in an ultrathin Fe80B20 layer sandwiched between two MgO barrier layers with different thicknesses, in which the bias voltage is predominantly applied to one of the MgO layers. The application of both positive and negative bias voltages enhanced the perpendicular anisotropy, in contrast with the odd function dependence previously observed in a MgO/ferromagnetic metal/non-magnetic metal structure. Moreover, for positive bias voltages, the large anisotropy change slope of 108 fJ/Vm was demonstrated. These results indicate that the MgO-sandwich structure has high potential to extend the availability of the voltage effect. (C) 2013 The Japan Society of Applied Physics