Magnetization Reversal by Coherent Spin Waves in Hybrid Ni₈₁Fe₁₉/SiO₂/Y₃Fe₅O₁₂ Nanostructures

Using short-wavelength spin waves (SWs) for an all-magnetic approach towards bit writing promise a major advance for in-memory wave-based computing platforms [1]. The first experimental report on the reversal of nanomagnets by travelling coherent SWs addressed mainly the power efficiency of one dipolar SW mode only [2]. Here we investigate the SW wavelength (λ) dependence of the magnetization reversal of individual 20-nm-thick Ni₈₁Fe₁₉ (Py) nanostripes integrated onto 113-nm-thick yttrium iron garnet (YIG). An intermediate SiO₂spacer between the YIG and the Py allows only for dipolar coupling and suppresses both exchange interaction and spin pumping. We observe the nanostripes reversal with SWs having different λ = 7222 nm, 195 nm and 148 nm. The critical power to initiate reversal shows a non-monotonic trend as a function of SW λ. The minimum critical power occurs at the λ matching the nanostripes’ periodicity. Our findings additionally prove that this reversal can be triggered by dipolar coupling between Py/YIG alone. Our results are encouraging towards the fabrication of a future magnetic memory where propagating SWs are writing magnetic bits without conversion to the electrical domain. Our work [3] further foster both materials and device optimisation to achieve a SW-based in-memory computing device.<br/>The research was supported by the Swiss National Science Foundation via grant number 197360.<br/><br/>[1] International roadmap for devices and systems. Tech. Rep. (2020).<br/>[2] Baumgaertl, K. and Grundler, D., 2023. <i>Nature Communications</i>, <i>14</i>(1), p.1490.<br/>[3] Mucchietto, A, Baumgaertl, K. and Grundler, D., 2024. <i>ACS nano</i> <i>18</i>(12), p.8641.