Magnetism and local structure in low-dimensional, Mott insulating GdTiO3

TL;DR

This study investigates how the structure and magnetism of GdTiO3 thin films change with thickness, revealing that ferromagnetism persists despite reduced distortions, influenced mainly by electronic interactions rather than structural distortions.

Contribution

It provides new insights into the relationship between local structure and magnetic properties in low-dimensional GdTiO3 films, emphasizing electronic factors over structural distortions.

Findings

Structural distortions decrease with film thickness.

Ferromagnetism persists at smaller distortions than in bulk.

Magnetic ground state is mainly controlled by electronic interactions.

Abstract

Cation displacements, oxygen octahedral tilts, and magnetism of epitaxial, ferrimagnetic, insulating GdTiO3 films sandwiched between cubic SrTiO3 layers are studied using scanning transmission electron microscopy and magnetization measurements. With decreasing GdTiO3 film thickness, structural (GdFeO3-type) distortions are reduced, concomitant with a reduction in the Curie temperature. Ferromagnetism persists to smaller deviations from the cubic perovskite structure than is the case for the bulk rare earth titanates. The results indicate that the FM ground state is controlled by the narrow bandwidth, exchange and orbital ordering, and only to second order depends on amount of the GdFeO3-type distortion.