The effect of spin currents on the magnetic order of insulating antiferromagnets (AFMs) is of fundamental interest and can enable new applications. Toward this goal, characterizing the spin-orbit torques (SOTs) associated with AFM–heavy-metal (HM) interfaces is important. Here we report the full angular dependence of the harmonic Hall voltages in a predominantly easy-plane AFM, epitaxial $c$-axis oriented $\alpha \text{−}{\text{Fe}}_2{\mathrm{O}}_3$ films, with an interface to Pt. By modeling the harmonic Hall signals together with the $\alpha \text{−}{\text{Fe}}_2{\mathrm{O}}_3$ magnetic parameters, we determine the amplitudes of fieldlike and dampinglike SOTs. Out-of-plane field scans are shown to be essential to determining the dampinglike component of the torques. In contrast to ferromagnetic–heavy-metal heterostructures, our results demonstrate that the fieldlike torques are significantly larger than the dampinglike torques, which we correlate with the presence of a large imaginary component of the interface spin-mixing conductance. Our work demonstrates a direct way of characterizing SOTs in AFM-HM heterostructures.

中文翻译：

---

量化反铁磁体-重金属异质结构中的自旋轨道扭矩

自旋电流对绝缘反铁磁体 (AFM) 磁序的影响具有重要意义，可以实现新的应用。为了实现这一目标，表征与 AFM-重金属 (HM) 界面相关的自旋轨道扭矩 (SOT) 非常重要。在这里，我们报告了在主要是易平面 AFM、外延的谐波霍尔电压的完整角度依赖性$C$-轴导向$\alpha \text{-}{\text{铁}}_2{\mathrm{○}}_3$电影，与铂的接口。通过将谐波霍尔信号与$\alpha \text{-}{\text{铁}}_2{\mathrm{○}}_3$磁参数，我们确定类场和类阻尼 SOT 的幅度。平面外场扫描被证明对于确定扭矩的阻尼类分量是必不可少的。与铁磁 - 重金属异质结构相比，我们的结果表明，类场扭矩明显大于类阻尼扭矩，这与界面自旋混合电导的大虚数分量的存在相关。我们的工作展示了一种直接表征 AFM-HM 异质结构中 SOT 的方法。