Research articles

This study explores a novel approach to achieve field-free current-driven spin–orbit torque switching of perpendicular magnetization for MRAM applications. By adjusting growth protocols in Pt-based magnetic heterostructures, a previously overlooked laterally tilted texture and magnetic anisotropy are harnessed. These findings allow deterministic switching of perpendicular magnetization without an external magnetic field. Contrary to conventional assumptions, the observed nonlinear dependence on current density resembles a damping-like torque, challenging previous notions about its origin.

Schematic illustrations of the changes in the magnetic anisotropy by an applied electric field (E) in the strain directions are displayed. Under an applied E, the piezoelectric stress in the ferroelectric PMN-PT could be introduced in the tensile and compressive directions using positive and negative bias voltages, respectively, resulting in the changes in the magnetic anisotropy in the Co₂FeSi layer. The XMCD spectra of Fe and Co L-edges in Co₂FeSi under applying E showed the line shape changes only in the Fe site, which corresponds to the changes of orbital magnetic moment in Fe, while that in Co remains unchanged.

The fabrication and development of high-entropy alloys (HEAs) with exceptional functionalities is a rapidly expanding field. The extrinsic factors, such as the existence of grains and different phases, would complicate understanding the physical phenomena. We classified the epitaxial system into atomic-site disordered (ASD) and amorphous system into structurally disordered (SD) states, respectively, to exclude the extrinsic effects of HEAs. With a comprehensive study of the magnetic and transport properties, we can further promote the research of high entropy systems.