Precise control of $J_\mathrm{eff}=1/2$ magnetic properties in Sr$_2$IrO$_4$ epitaxial thin films by variation of strain and thin film thickness

TL;DR

This study demonstrates how strain and film thickness can be used to precisely control the magnetic properties of Sr$_2$IrO$_4$ thin films, revealing a transition from 2D to 3D magnetic behavior.

Contribution

It provides a systematic analysis of how strain and thickness influence magnetic correlations in Sr$_2$IrO$_4$ thin films, highlighting the ability to tune magnetic anisotropy.

Findings

Magnetic correlation length depends on film thickness, not strain.

Films can be grown fully strained up to 108 nm thickness.

Magnetic anisotropy transitions from 2D to 3D with increasing thickness.

Abstract

We report on a comprehensive investigation of the effects of strain and film thickness on the structural and magnetic properties of epitaxial thin films of the prototypal $J_\mathrm{eff}=1/2$ compound Sr$_2$IrO$_4$ by advanced X-ray scattering. We find that the Sr$_2$IrO$_4$ thin films can be grown fully strained up to a thickness of 108 nm. By using X-ray resonant scattering, we show that the out-of-plane magnetic correlation length is strongly dependent on the thin film thickness, but independent of the strain state of the thin films. This can be used as a finely tuned dial to adjust the out-of-plane magnetic correlation length and transform the magnetic anisotropy from two-dimensional (2D) to three-dimensional (3D) behavior by incrementing film thickness. These results provide a clearer picture for the systematic control of the magnetic degrees of freedom in epitaxial thin films of Sr$_2$IrO$_4$ and bring to light the potential for a rich playground to explore the physics of $5d$-transition metal compounds.