Layer-Resolved Magnetization Reversal via an Interlayer Coupling

Multi-state functionality with high energy efficiency is one of the essential characteristics of designing neuromorphic and in-memory computing applications. In spintronics, this issue holds significant importance, especially given that magnetic material systems exhibit the advantage of being non-volatile, energy efficient, and easy to control by the magnetic field or current. This study investigates the complete multi-level reversals of Pt/ Co-based multilayer with perpendicular magnetic anisotropy. By adjusting the thickness of the Pt, we obtain a suitable condition to control the interlayer couplings. This allows layer-resolved magnetization reversals, which indicates that each layer switches independently and sequentially rather than simultaneously. By employing appropriate external magnetic field sequences, we induced the entire eight states of the multilayer system in the remanence and established a method for transitions between these states. Since the magnetic field sequences can be replaced by spin-transfer torque or spin-orbit torque sequences, our work demonstrates a prominent method for storing three-bit non-volatile memory. Furthermore, our work leads to practical ways of establishing interlayer coupling can achieve parallel or antiparallel alignment between magnetizations of ferromagnetic multilayer film.