Orientation-dependent magnetism and orbital structure of strained YTiO$_3$ films on LaAlO$_3$ substrates

TL;DR

This study uses first-principles calculations to reveal how the orientation of strained YTiO₃ films on LaAlO₃ substrates drastically affects their magnetic and orbital properties, showing ferromagnetism in one orientation and antiferromagnetism in another.

Contribution

It demonstrates the orientation-dependent magnetism and orbital structure of YTiO₃ films, highlighting the role of orbital ordering and lattice mismatch effects.

Findings

Ferromagnetic for (110) orientation

A-type antiferromagnetic for (001) orientation

Orbital ordering differences explain magnetic behavior

Abstract

The strain tuned magnetism of YTiO$_3$ film grown on the LaAlO$_3$ ($110$) substrate is studied by the method of the first principles, and compared with that of the ($001$)-oriented one. The obtained magnetism is totally different, which is ferromagnetic for the film on the ($110$) substrate but A-type antiferromagnetic on the ($001$) one. This orientation-dependent magnetism is attributed to the subtle orbital ordering of YTiO$_3$ film. The $d_{xz}$/$d_{yz}$-type orbital ordering is predominant for the ($001$) one, but for the ($110$) case, the $d_{xy}$ orbital is mostly occupied plus a few contribution from the $d_{xz}$/$d_{yz}$ orbital. Moreover, the lattice mismatch is modest for the ($110$) case but more serious for the ($001$) one, which is also responsible for this contrasting magnetism.