Electrical Manipulation of Field-Free Magnetization Switching Driven by Spin-Orbit Torque in Amorphous Gradient-Mn₃Sn

Switching the magnetization without an assisted magnetic field is crucial for the application of spin-orbit torque (SOT) devices. However, the realization of field-free magnetization switching usually calls for intricate design and growth of heterostructure. In this study, it is found that the amorphous Mn₃Sn can generate a highly efficient spin current with a strong z-direction polarization component due to its spontaneous composition gradient, which switches the perpendicular magnetization in the absence of an external field. The SOT efficiency of gradient-Mn₃Sn can be reversibly modulated by the ionic liquid gating based on the migration of hydrogen ions, which reverses the polarity of field-free magnetization switching and allows the realization of 16 binary Boolean logic functions in a single device by pure electrical methods. These results not only offer a very convenient route to field-free magnetization switching but also can promote the development of in-memory computing for spintronic devices.