RKKY coupling effect on Spin-orbit torque switching in a L10 FePt-gradient film*

Spin–orbit torque (SOT)-induced magnetic switching has attracted much interest due to its potentially high efficiency in terms of switching time and power consumption, energy efficiency and high endurance. The L1₀ FePt is representative material as the mainstay of magnetic data storage media owing to its high thermal stability for more than 10-year retention and their amenability to miniaturization. For the SOT switching, a structural inversion asymmetry and strong spin-orbit coupling are generally essential.

In the presentation, we discuss the effect of RKKY interaction on the SOT switching characteristics FePt L1₀ with composition gradient. Composition gradient gives structural asymmetry in the FePt L1₀, resulting in spin current generation with strong perpendicular magnetic anisotropy (PMA). In order to use the FePt L1₀ with composition gradient for the magnetic tunnel junction application, RKKY coupling with CoFeB is demanded as well as its strong PMA because of high tunneling magnetoresistance. Our study will provide a way to utilize FePt L1₀ structure for magnetic random access memory applications.