Possible origin of nonlinear magnetic anisotropy variation in electric   field effect in a double interface system
  We investigated the effect of an electric field on the interface magnetic anisotropy of a thin MgO/Fe/MgO layer using density functional theory. The perpendicular magnetic anisotropy energy (MAE) increases not only under electron depletion but also under some electron accumulation conditions, showing a strong correlation with the number of electrons on the interface Fe atom. The reverse variation in the MAE under the electric field is ascribed to novel features on the charged interface, such as electron leakage. We discuss the origin of the variation in terms of the electronic structures. 
Daiki Yoshikawa, Masao Obata, Yusaku Taguchi, Shinya Haraguchi, and   Tatsuki Oda
cond-mat.mtrl-sci physics.comp-ph