Interlayer-Exchange-Dominant Spin Hall Nano-Oscillator

The spin Hall nano-oscillator (SHNO) is a promising spintronic device to produce high-frequency and low-linewidth microwave signals. We study a type of SHNO based on the L10-FePt/NiFe/Pt exchange-spring system with an ultrahigh perpendicular magnetic anisotropy by micromagnetic simulation. The hard-soft magnetic exchange-spring system has a very high interlayer-exchange-interaction field, result-ing in a more than 30-GHz emission frequency and 38.6-GHz/T field tunability. Apart from conventional localized and nonlocalized auto-oscillation modes, localized or nonlocalized modes with central antisym-metry also appear in this SHNO. Two oscillation centers possess nonequal amplitudes and opposite phases in these antisymmetrical modes. Different modes are determined by the competition between three fac-tors: the exchange-interaction field, the perpendicular anisotropic field, and spin-orbit torque. The spin dynamics in the SHNO exhibit complex field and current dependence. Our results provide a possible direction for the design of SHNOs, which may be beneficial for the research and development of spintronic nano-oscillators.