Observation of Compensation Temperature in Epitaxial Tm₃Fe₅O₁₂ Thin Films by Polar Magneto-Optic Kerr Effect

Since ferrimagnetic rare-earth iron garnets (RIG) R₃Fe₅O₁₂ are excellent insulators with Curie temperatures well above room temperature, such materials have been extensively exploited in spintronics, leading to novel discoveries such as anomalous Hall effect in the heterostructure formed by topological insulator and Tm₃Fe₅O₁₂ (TmIG). While the recent research on TmIG thin films has been focusing on the behavior of their perpendicular magnetic anisotropy (PMA) in high temperature region, the magnetic properties of TmIG thin films at lower temperatures are elusive. In this report, we measured the low temperature magnetic properties of epitaxial TmIG films by polar magneto-optic Kerr effect. The divergence of the out-of-plane coercive filed and the reverse of the sign of out-of-plane magnetization were observed consecutively, indicating the existence of compensation temperature in TmIG. Further investigation showed that the temperature making divergent was dependent on the thickness and strain state of the film. Since the compensation temperature in bulk TmIG has never been established, our findings demonstrate that it is worth investigating low temperature magnetism in low dimensional rare-earth iron garnets to advance the research of RIG-based spintronics.