We use micro-focus Brillouin light scattering spectroscopy to study the effects of spin-orbit torque on thermal spin waves in almost angular-momentum compensated ferrimagnetic CoGd alloy films. The spin-orbit torque is produced by the electric current flowing in the Pt layer adjacent to CoGd. Both the ferromagnetic and the exchange modes are detected in our measurements. The intensity and the linewidth of the ferromagnetic mode are modified by the spin-orbit torque. In contrast, the properties of the exchange mode are unaffected by the spin-orbit torque. We also find that the frequencies and the linewidths of both modes are significantly modified by Joule heating, due to the strong temperature dependence of the magnetic properties of CoGd in the vicinity of angular momentum compensation point. Our results provide insight into the mechanisms that can enable the implementation of sub-THz magnetic nano-oscillators based on ferrimagnetic materials, as well as related effects in antiferromagnets.

中文翻译：

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自旋轨道转矩对铁磁CoGd合金中铁磁和交换自旋波模式的影响

我们使用布里渊微焦点光散射光谱法研究自旋轨道转矩对几乎角动量补偿的亚铁磁CoGd合金薄膜中热自旋波的影响。自旋轨道转矩是由在与CoGd相邻的Pt层中流动的电流产生的。在我们的测量中，铁磁和交换模式都被检测到。铁磁模式的强度和线宽由自旋轨道转矩修改。相反，交换模式的特性不受自旋轨道转矩的影响。我们还发现，由于角动量补偿点附近CoGd磁性的强烈温度依赖性，焦耳加热极大地改变了两种模式的频率和线宽。