Evolution of magnetic phases and orbital occupation in (SrMnO3)n/(LaMnO3)2n superlattices

TL;DR

This study investigates how magnetic phases and orbital occupations evolve in (SrMnO3)n/(LaMnO3)2n superlattices, revealing interface-driven ferromagnetism and orbital preferences influenced by strain and layer thickness.

Contribution

It provides new insights into the interface-induced magnetic and orbital modifications in superlattices, combining experimental spectroscopy with theoretical calculations.

Findings

Charge redistribution favors in-plane ferromagnetism and specific orbital occupation.

Far from interfaces, antiferromagnetism and different orbital occupation dominate.

Layer thickness influences the magnetic order and orbital occupation distribution.

Abstract

The magnetic and electronic modifications induced at the interfaces in (SrMnO$_{3}$)$_{n}$/(LaMnO$_{3}$)$_{2n}$ superlattices have been investigated by linear and circular magnetic dichroism in the Mn L$_{2,3}$ x-ray absorption spectra. Together with theoretical calculations, our data demonstrate that the charge redistribution across interfaces favors in-plane ferromagnetic (FM) order and $e_{g}(x^{2}-y^{2})$ orbital occupation, in agreement with the average strain. Far from interfaces, inside LaMnO$_3$, electron localization and local strain favor antiferromagnetism (AFM) and $e_{g}(3z^{2}-r^{2})$ orbital occupation. For $n=1$ the high density of interfacial planes ultimately leads to dominant FM order forcing the residual AFM phase to be in-plane too, while for $n \geq 5$ the FM layers are separated by AFM regions having out-of-plane spin orientation.