Fieldlike torque driven switching in rare-earth transition-metal alloys

Spin-orbit torque (SOT) has been widely recognized and applied as the most promising approach for magnetic memory, primarily due to its lower energy consumption and longer device lifetime. However, the mechanism of SOT remains controversial in ferrimagnets, particularly regarding the role of fieldlike torque (FLT). This uncertainty arises from the presence of different gyromagnetic ratios of the sublattices, which generates significant variations particularly in the vicinity of the angular momentum compensation point. In this paper, we demonstrate that, in the vicinity of the angular momentum compensation point, FLT can act as a main driving term for magnetization switching in ferrimagnets through rigorous mathematical analysis and ferrimagnetic macrospin simulation. We also provide clear indications about the materials damping factor on how to tailor the magnetic layer where a charge current is injected. These findings shed light on the intricate behavior of SOT in ferrimagnetic systems and pave a way for further advancements in high-performance magnetic memory devices.