Perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction at an oxide/ferromagnetic metal interface

TL;DR

This study investigates how the termination layer of BaTiO3 influences perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction at BaTiO3/CoFeB interfaces, revealing key electronic and spin phenomena relevant for energy-efficient spintronic devices.

Contribution

It demonstrates the dominant role of oxide termination in tuning magnetic properties at oxide/FM interfaces through combined experimental and first-principles analysis.

Findings

BaO termination doubles interfacial magnetic anisotropy energy.

TiO2 termination results in larger DMI.

Electronic states and spin-flip processes explain the observed effects.

Abstract

We report on the study of both perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii-Moriya interaction (DMI) at an oxide/ferromagnetic metal (FM) interface, i.e. BaTiO3 (BTO)/CoFeB. Thanks to the functional properties of the BTO film and the capability to precisely control its growth, we are able to distinguish the dominant role of the oxide termination (TiO2 vs BaO), from the moderate effect of ferroelectric polarization in the BTO film, on the PMA and DMI at the oxide/FM interface. We find that the interfacial magnetic anisotropy energy of the BaO-BTO/CoFeB structure is two times larger than that of the TiO2-BTO/CoFeB, while the DMI of the TiO2-BTO/CoFeB interface is larger. We explain the observed phenomena by first-principles calculations, which ascribe them to the different electronic states around the Fermi level at the oxide/ferromagnetic metal interfaces and the different spin-flip processes. This study paves the way for further investigation of the PMA and DMI at various oxide/FM structures and thus their applications in the promising field of energy-efficient devices.