Loss of anisotropy in strained ultrathin epitaxial L10 Mn-Ga films

TL;DR

This study investigates how strain affects the magnetic perpendicular anisotropy in ultrathin Mn-Ga films, revealing that strain reduces anisotropy but can be mitigated with a Pt buffer, enabling thinner films with high magnetic stability.

Contribution

It demonstrates the impact of strain on magnetic properties in ultrathin Mn-Ga films and shows how buffer layers can preserve anisotropy at reduced thicknesses.

Findings

Strain reduces perpendicular magnetic anisotropy in ultrathin Mn-Ga films.

Introducing a Pt buffer layer alleviates strain effects, maintaining high anisotropy at 6nm thickness.

The c/a ratio correlates with strain and magnetic properties in these films.

Abstract

In this work we are investigating the effect of strain in ultrathin Mn-Ga thin films on the magnetic properties at room temperature. Two different Mn-Ga compositions of which one is furthermore doped with Co were grown on Cr buffered MgO (001) substrates. Films with a thickness below 12nm are highly strained and it was observed that the ratio c/a vs. thickness is depending on composition. Using c/a as an order parameter the PMA is shown to be drastically reduced with increasing strain. These findings should be considered when generalizing and downscaling results obtained from films >20nm. Furthermore it has been shown, that the strain can be reduced by introducing an additional Pt buffer and thus maintaining a high PMA for a thickness as low as 6nm.