Huang Lin, Cao Yanzhang, Qiu Hongsong, Bai Hua, Liao Liyang, Chen Chong, Han Lei, Pan Feng, Jin Biaobing, Song Cheng
Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China.
State Key Laboratory of Spintronics Devices and Technologies, School of Integrated Circuits, Nanjing University, Suzhou, China.
Nat Commun. 2024 Aug 22;15(1):7227. doi: 10.1038/s41467-024-51440-4.
Antiferromagnets are promising for nano-scale oscillator in a wide frequency range from gigahertz up to terahertz. Experimentally realizing antiferromagnetic moment oscillation via spin-orbit torque, however, remains elusive. Here, we demonstrate that the optical spin-orbit torque induced by circularly polarized laser can be used to drive free decaying oscillations with a frequency of 2 THz in metallic antiferromagnetic MnAu thin films. Due to the local inversion symmetry breaking of MnAu, ultrafast a.c. current is generated via spin-to-charge conversion, which can be detected through free-space terahertz emission. Both antiferromagnetic moments switching experiments and dynamics analyses unravel the antiferromagnetic moments, driven by optical spin-orbit torque, deviate from its equilibrium position, and oscillate back in 5 ps once optical spin-orbit torque is removed. Besides the fundamental significance, our finding opens a new route towards low-dissipation and controllable antiferromagnet-based spin-torque oscillators.
反铁磁体在从吉赫兹到太赫兹的宽频率范围内有望用于纳米级振荡器。然而，通过自旋轨道扭矩在实验上实现反铁磁矩振荡仍然难以捉摸。在这里，我们证明了圆偏振激光诱导的光学自旋轨道扭矩可用于驱动金属反铁磁MnAu薄膜中频率为2太赫兹的自由衰减振荡。由于MnAu的局部反演对称性破缺，通过自旋到电荷的转换产生超快交流电流，这可以通过自由空间太赫兹发射检测到。反铁磁矩切换实验和动力学分析都表明，由光学自旋轨道扭矩驱动的反铁磁矩偏离其平衡位置，一旦去除光学自旋轨道扭矩，会在5皮秒内振荡回来。除了具有基本意义外，我们的发现为低耗散和可控的基于反铁磁体的自旋扭矩振荡器开辟了一条新途径。
