Resolving weak moments in canted antiferromagnets via time-domain terahertz emission spectroscopy
- Xuyang Sha
- Tongyang Guan
- Zhen Wang
- Zhengkun Li
- Shunjia Wang
- Zhangshun Li
- Chen Huang
- Zuanming Jin
- Zhe Yuan
- Zhensheng Tao
- Hangwen Guo
- Jian Shen
2026-07-24
Canted antiferromagnets host weak net magnetization arising from spin canting while preserving the ultrafast response of antiferromagnetic order. Probing such minute moments—especially in thin films—remains challenging, as conventional magneto-optical and electrical techniques lack sufficient sensitivity. Here, we employ time-domain terahertz emission spectroscopy as a contact-free probe of such weak magnetism. Using epitaxial TmFeO 3 /Pt heterostructures as a model system, the emitted THz signal directly follows the orientation of the canted Fe 3+ moment, allowing real-time tracking of its continuous rotation through the spin reorientation transition. Moreover, the THz hysteresis polarity is reversed compared with conventional ferromagnet/Pt systems, indicating an unconventional interfacial magnetic configuration. Our findings establish THz emission spectroscopy as a powerful tool for resolving ultrafast THz emission response in canted antiferromagnetic thin and ultrathin films.