Zhang De-Lin, Zhu Jie, Qu Tao, Lattery Dustin M, Victora R H, Wang Xiaojia, Wang Jian-Ping
Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
Sci Adv. 2020 Sep 18;6(38). doi: 10.1126/sciadv.abb4607. Print 2020 Sep.
It is desirable to experimentally demonstrate an extremely high resonant frequency, assisted by strain-spin coupling, in technologically important perpendicular magnetic materials for device applications. Here, we directly observe the coupling of magnons and phonons in both time and frequency domains upon femtosecond laser excitation. This strain-spin coupling leads to a magnetoacoustic resonance in perpendicular magnetic [Co/Pd] multilayers, reaching frequencies in the extremely high frequency (EHF) band, e.g., 60 GHz. We propose a theoretical model to explain the physical mechanism underlying the strain-spin interaction. Our model explains the amplitude increase of the magnetoacoustic resonance state with time and quantitatively predicts the composition of the combined strain-spin state near the resonance. We also detail its precise dependence on the magnetostriction. The results of this work offer a potential pathway to manipulating both the magnitude and timing of EHF and strongly coupled magnon-phonon excitations.
期望在技术上重要的用于器件应用的垂直磁性材料中，通过应变 - 自旋耦合实验证明极高的共振频率。在此，我们在飞秒激光激发下，直接在时域和频域中观察到磁振子与声子的耦合。这种应变 - 自旋耦合导致垂直磁性[Co/Pd]多层膜中的磁声共振，达到极高频（EHF）波段的频率，例如60 GHz。我们提出了一个理论模型来解释应变 - 自旋相互作用背后的物理机制。我们的模型解释了磁声共振状态的振幅随时间增加的现象，并定量预测了共振附近组合应变 - 自旋状态的组成。我们还详细说明了其对磁致伸缩的精确依赖性。这项工作的结果为操纵EHF的幅度和时间以及强耦合磁振子 - 声子激发提供了一条潜在途径。
