Field‐Free Switching and Enhanced Electrical Detection of Ferrimagnetic Insulators Through an Intermediate Ultrathin Ferromagnetic Metal Layer

Abstract Perpendicularly magnetized ferrimagnetic insulators offer great potential for the development of fast and energy‐efficient spintronic devices. However, a major challenge for these devices is the requirement of an auxiliary magnetic field to achieve spin‐orbit torque (SOT)‐driven magnetization switching, along with the extremely small electric read‐out signal from the adjacent heavy metal layer. In this work, an approach by introducing an ultrathin Co layer primarily with in‐plane magnetization at the interface of the Tm 3 Fe 5 O 12 /Pt bilayers, which enables field‐free deterministic switching of the perpendicular Tm 3 Fe 5 O 12 layer is demonstrated. Meanwhile, it is observed that a large anomalous Hall resistance readout signal from the coupling‐induced perpendicular component of the interfacial Co, which is nearly two orders of magnitude larger than that observed in Tm 3 Fe 5 O 12 /Pt bilayers. The crucial role played by the Co layer in modifying the SOT is elucidated. This research represents a significant step toward the practical implementation of ferrimagnetic insulator devices.