Strain-Tunable Magnetic Compensation Temperature of Epitaxial Tb$_3$Fe$_5$O$_{12}$ Thin Films

TL;DR

This study demonstrates that applying strain to epitaxial Tb$_3$Fe$_5$O$_{12}$ thin films can tune their magnetic compensation temperature, with implications for optimizing spin-orbit torque devices.

Contribution

The paper shows how substrate-induced strain in epitaxial TbIG films can control their magnetic compensation temperature through experimental measurements and density functional theory calculations.

Findings

Compensation temperature varies monotonically with strain.

Strain affects exchange interactions between magnetic atoms.

Theoretical calculations match experimental observations.

Abstract

High-quality rare-earth iron garnet (ReIG) Tb$_3$Fe$_5$O$_{12}$ (TbIG) thin films are epitaxially grown on a series of (111)-oriented garnet substrates with various lattice constants. The coherent growth induces a substrate-dependent in-plane tensile or compressive strain in the TbIG film. Measurements of the anomalous Hall-like effect (AHLE) in TbIG/Pt heterostructures show that the compensation temperature of TbIG films monotonically changes with the film strain. The strain results in a variation of the distances between magnetic atoms in the TbIG crystal and therefore the corresponding exchange interactions. The latter is explicitly calculated as a function of the lattice strain based on density functional theory, reproducing the observed experimental results. This work provides a versatile way to optimize ReIG-based spin-orbit torque devices.