High magnon modulation with low current density in thin film lithium aluminum ferrite (Li_0.5Al_1.0Fe_1.5O₄)

Spin wave-based spintronics are an alternative to conventional electronics due to their potential for efficient energy consumption, improved processing speed and smaller device dimensions. The success of spin wave spintronics relies on the existence of low damping magnetic insulators that allow for efficient spin wave generation, manipulation, and detection. A promising candidate is the recently developed thin film Li_0.5Al_1.0Fe_1.5O₄ (LAFO) with low Gilbert damping parameter on the order of 10^-4 in 15 nm thick LAFO. In this talk, we present our results on non-local magnon transport in Li_0.5Al_1.0Fe_1.5O₄(LAFO), a magnetic insulator, grown on (100) oriented MgAl₂O₄(MAO). By studying the non-local voltage amplitude generated via the inverse spin Hall effect as a function of the separation of two overlaying Pt electrodes, we deduce a spin diffusion length in 15 nm thick LAFO of 1.9 um which is consistent with our previous results. By adding a third DC bias Pt electrode (modulator) between the two Pt electrodes, we can modulate the non-local voltage amplitude by a factor of 3.5 with current densities on the order of 10¹¹ A/cm², significantly lower than the current densities needed to achieve the same modulation in Y₃Fe₅O₁₂ (YIG). Additionally, from the relationship between the voltage amplitude and DC bias current, we can extract a critical current I_c, where the damping-like torque on the magnons underneath the Pt electrode is fully compensated by the spin-orbit torque from Pt. I_c is monotonically related to the width of the modulator which is in good agreement with theoretical predictions. These results show the promise of spin waves as a new platform for information processing.