We report results of micro-Brillouin-Mandelstam light scattering spectroscopy of thermal magnons in the two-phase synthetic multiferroic structure consisting of a piezoelectric (PMN-PT) substrate and a Ni thin film with the thickness of 64 nm. The experimental data reveal the first two modes of the perpendicular standing spin waves (PSSW) spatially confined across the Ni thin film. A theoretical analysis of the frequency dependence of the PSSW peaks on the external magnetic field reveals the asymmetric boundary condition, i.e. pinning, for variable magnetization at different surfaces of the Ni thin film. The strain field induced by applying DC voltage to PMN-PT substrate leads to a down shift of PSSW mode frequency owing to the magneto-elastic effect in Ni, and corresponding changes in the spin wave resonance conditions. The observed non-monotonic dependence of the PSSW frequency on DC voltage is related to an abrupt change of the pinning parameter at certain values of the voltage. The obtained results are important for understanding the thermal magnon spectrum in ferromagnetic films and development of the low-power spin-wave devices.

中文翻译：

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压电衬底上镍薄膜中应力调制空间受限自旋波的布里渊-曼德尔斯坦光谱

我们报告了由压电 (PMN-PT) 基板和厚度为 64 nm 的 Ni 薄膜组成的两相合成多铁结构中热磁振子的微布里渊-曼德尔斯坦光散射光谱的结果。实验数据揭示了空间限制在 Ni 薄膜上的垂直自旋驻波 (PSSW) 的前两种模式。PSSW 峰值对外部磁场的频率依赖性的理论分析揭示了非对称边界条件，即钉扎，用于在 Ni 薄膜的不同表面进行可变磁化。由于 Ni 中的磁弹性效应，将 DC 电压施加到 PMN-PT 衬底上引起的应变场导致 PSSW 模式频率的下移，以及自旋波共振条件的相应变化。观察到的 PSSW 频率对 DC 电压的非单调依赖性与特定电压值下钉扎参数的突然变化有关。获得的结果对于理解铁磁薄膜中的热磁振子光谱和开发低功率自旋波器件具有重要意义。