Temperature dependence of higher-order magnetic anisotropy constants and voltage-controlled magnetic anisotropy effect in a Cr/Fe/MgO junction

Abstract

The temperature dependence of the first- A nd second-order magnetic anisotropies, K u1 and K u2, was studied with a view to investigating the voltage-controlled magnetic anisotropy (VCMA) effect in Cr/ultrathin Fe/MgO structures. The K u1 term increased with decreasing temperature, whereas the K u2 term exhibited relatively small temperature dependence. The VCMA coefficient in the K u1 term increased while that in the K u2 term decreased at low temperature. Moreover, the signs of the VCMA coefficient for K u1 and K u2 were opposite signs and compensated each other, the trend of which provides evidence of enhancement of the effective VCMA coefficient at low temperature.