An Etching-Free Strategy for Highly Spin Transparent Yttrium Iron Garnet Surfaces Using an Ultrathin Fe ₂ O ₃ Sacrificial Layer

Due to its ultralow magnetic damping, yttrium iron garnet (YIG) film is widely employed in spintronic devices, especially for spin current generation. However, experimental studies have consistently revealed the formation of a thin, poorly crystallized yttrium-rich layer on the top surface of fabricated YIG films, which can significantly impede spin transparency. To address this issue, we propose using an ultrathin amorphous Fe 2 O 3 layer grown directly on the YIG film at room temperature as a sacrificial layer, to compensate for the Fe deficiency in the YIG film that occurs during the high-temperature annealing process. The feasibility of this approach has been demonstrated through comprehensive structural, chemical, and magnet-transport studies. In contrast to previously reported post-treatment methods such as ion beam etching or wet acid solution etching, our approach is etching-free and thus offers significantly better compatibility.