The origin of enhanced interfacial perpendicular magnetic anisotropy in LiF-inserted Fe/MgO interface

TL;DR

This paper investigates how inserting a LiF layer at the Fe/MgO interface enhances perpendicular magnetic anisotropy by increasing orbital-magnetic-moment anisotropy, linked to improved interface quality and electron localization.

Contribution

It provides experimental evidence that LiF insertion enhances PMA through increased orbital-magnetic-moment anisotropy and improved interface quality.

Findings

LiF insertion increases orbital-magnetic-moment anisotropy.

Enhanced PMA linked to better interface quality and electron localization.

Stronger electron-electron correlation contributes to anisotropy enhancement.

Abstract

The Fe/MgO interface is an essential ingredient in spintronics as it shows giant tunneling magnetoresistance and strong perpendicular magnetic anisotropy (PMA). A recent study demonstrated that the insertion of an ultra-thin LiF layer between the Fe and MgO layers enhances PMA significantly. In this study, we perform x-ray magnetic circular dichroism measurements on Fe/LiF/MgO multilayers to reveal the origin of the PMA enhancement. We find that the LiF insertion increases the orbital-magnetic-moment anisotropy and thus the magnetic anisotropy energy. We attribute the origin of this orbital-magnetic-moment-anisotropy enhancement to the stronger electron localization and electron-electron correlation or the better interface quality with fewer defects.