Electrical switching of antiferromagnets is an exciting recent development in spintronics, which promises active antiferromagnetic devices with high speed and low energy cost. In this emerging field, there is an active debate about the mechanisms of current-driven switching of antiferromagnets. For heavy-metal/ferromagnet systems, harmonic characterization is a powerful tool to quantify current-induced spin-orbit torques and spin Seebeck effect and elucidate current-induced switching. However, harmonic measurement of spin-orbit torques has never been verified in antiferromagnetic heterostructures. Here, we report harmonic measurements in Pt/α-Fe₂O₃ bilayers, which are explained by our modeling of higher-order harmonic voltages. As compared with ferromagnetic heterostructures where all current-induced effects appear in the second harmonic signals, the damping-like torque and thermally-induced magnetoelastic effect contributions in Pt/α-Fe₂O₃ emerge in the third harmonic voltage. Our results provide a new path to probe the current-induced magnetization dynamics in antiferromagnets, promoting the application of antiferromagnetic spintronic devices.

反铁磁体的电转换是自旋电子学中令人兴奋的最新发展，它有望实现具有高速和低能量成本的有源反铁磁装置。在这个新兴领域，关于电流驱动的反铁磁体切换机制存在着激烈的争论。对于重金属/铁磁体系统，谐波表征是量化电流引起的自旋轨道转矩和自旋塞贝克效应以及阐明电流引起的切换的有力工具。然而，自旋轨道转矩的谐波测量从未在反铁磁异质结构中得到验证。在这里，我们报告了 Pt/ α -Fe ₂ O ₃中的谐波测量双层，这可以通过我们对高阶谐波电压的建模来解释。与所有电流感应效应都出现在二次谐波信号中的铁磁异质结构相比，Pt/ α -Fe ₂ O ₃中的类阻尼转矩和热感应磁弹性效应贡献出现在三次谐波电压中。我们的研究结果为探索反铁磁体中电流诱导的磁化动力学提供了一条新途径，促进了反铁磁自旋电子器件的应用。