Interface resonance in Fe/Pt/MgO multilayer structure with large voltage controlled magnetic anisotropy change

Abstract

Electric control of magnetism has been a topic of interest for various spintronic applications. It is known that monoatomic Pt layer insertion at the Fe/MgO interface increases voltage-controlled magnetic anisotropy (VCMA). However, the reason for the optimality of this thickness has not been explained thus far. In this study, we observed the changes in the electronic states at the Fe/MgO interface using tunneling spectroscopy on an epitaxial Fe(001)/Pt/MgO(001) structure to characterize the density of states around the Fermi level. We found that a surface resonant state is formed at the Fermi level by the insertion of a monoatomic Pt layer, which is consistent with our first principles study. In addition, the VCMA enhancement owing to the formation of this surface resonance state agrees with the recently proposed microscopic theory.Electric control of magnetism has been a topic of interest for various spintronic applications. It is known that monoatomic Pt layer insertion at the Fe/MgO interface increases voltage-controlled magnetic anisotropy (VCMA). However, the reason for the optimality of this thickness has not been explained thus far. In this study, we observed the changes in the electronic states at the Fe/MgO interface using tunneling spectroscopy on an epitaxial Fe(001)/Pt/MgO(001) structure to characterize the density of states around the Fermi level. We found that a surface resonant state is formed at the Fermi level by the insertion of a monoatomic Pt layer, which is consistent with our first principles study. In addition, the VCMA enhancement owing to the formation of this surface resonance state agrees with the recently proposed microscopic theory.