Magnetization dynamics in CoFe/Pt nanowires on lithium aluminum ferrite based hybrid spin-Hall nano-oscillators.

Spin-Hall nano-oscillators (SHNO) are of great interest for potential applications in microwave frequency spin wave devices. Of the auto-oscillation modes in SHNOs, propagating spin wave modes have attracted considerable interest due to their potential to create long-range coupling between SHNOs and harness phase control, which is critical for neuromorphic computing and magnonic device development. A recent experimental study demonstrated hybrid SHNO incorporating low-damping lithium aluminum spinel ferrite (LAFO). It was shown that hybrid SHNO have lower threshold currents and enhanced emission power but the experimental results and modeling suggest the auto-oscillation modes were localized. However, it is predicted that hybrid oscillators can be designed to host propagating spin waves. Here study magnetization dynamics in a hybrid SHNO of Co₂₅Fe₇₅/Pt nanowires on Li_0.5Al_xFe_2.5-xO₄ thin films. Ferromagnetic resonance (FMR) and spin-torque FMR are conducted to determine their properties. The results show that Co₂₅Fe₇₅/Pt nanowires have Gilbert damping of 0.0045 and saturation magnetization of 2.59 T. The low damping and the saturation magnetization of CoFe, which can be higher than LAFO, make Pt/CoFe/LAFO a promising material combination for hybrid SHNO that hosts propagating spin waves.