Deterministic Magnetization Switching with Controllable Chirality in Single Sperimagnetic NiFeTb Layers

Abstract

Field-free magnetization switching with low critical current density is a fundamental pursuit for spin-orbit torque (SOT) devices. Here, a novel strategy is provided that utilizes the sperimagnetism of NiFeTb to achieve current-induced field-free magnetization switching with high efficiency and controllable chirality. The critical current density required for field-free magnetization switching is as low as 2.8 × 10⁶ A cm⁻², an order of magnitude lower than that in conventional heavy metal-based magnetic heterostructures. The ultralow critical current density is attributed to the exceptional soft magnetism, the nucleation-dominant switching characteristic of NiFeTb, and the strong spin Hall effect associated with the large spin-orbital coupling of Tb 4f electrons. Notably, the switching chirality can be designed by manipulating the history of the in-plane magnetic field. The field-free and chirality-controlled magnetization switching in NiFeTb is facilitated by the symmetry-broken sperimagnetic structural arrangement. Utilizing the rich intermediate resistance states and non-volatility of the device, neural network computation is simulated. The findings reveal sperimagnetic rare-earth-transition metal alloys as vital candidates for multifunctional, ultra-low-power storage and computing applications.