Aluminium substituted yttrium iron garnet thin films with reduced Curie temperature

TL;DR

This study demonstrates the successful fabrication of aluminum-substituted yttrium iron garnet thin films with tunable magnetic properties, including reduced Curie temperatures, suitable for advanced spintronic and magnonic applications.

Contribution

It introduces a new method to grow highly crystalline Al-substituted yttrium iron garnet thin films with controllable magnetic phase transitions.

Findings

Al-substituted yttrium iron garnet films were successfully grown.

Increasing Al$^{3+}$ levels reduce saturation magnetization.

Curie temperature decreases with higher Al substitution.

Abstract

Magnetic garnets such as yttrium iron garnet (Y$_3$Fe$_5$O$_{12}$, YIG) are widely used in spintronic and magnonic devices. Their magnetic and magneto-optical properties can be modified over a wide range by tailoring their chemical composition. Here, we report the successful growth of Al-substituted yttrium iron garnet (YAlIG) thin films via radio frequency sputtering in combination with an ex situ annealing step. Upon selecting appropriate process parameters, we obtain highly crystalline YAlIG films with different Al$^{3+}$ substitution levels on both, single crystalline Y$_3$Al$_5$O$_{12}$ (YAG) and Gd$_3$Ga$_5$O$_{12}$ (GGG) substrates. With increasing Al$^{3+}$ substitution levels, we observe a reduction of the saturation magnetisation as well as a systematic decrease of the magnetic ordering temperature to values well below room temperature. YAlIG thin films thus provide an interesting material platform for spintronic and magnonic experiments in different magnetic phases.