Decoding the Mechanism and Coherent Control of Ultrafast Magnetism

Coherent manipulation of quantum material phases via lattice degree of freedom presents a versatile route for exploring hidden phases and enabling advanced functionalities. While ultrafast switching on of a millisecond time-scale metastable magnetization has been demonstrated in FePS₃, its underlying mechanism has yet to be fully understood. Here, we employed terahertz double-pump experiments and two-dimensional terahertz spectroscopy to decode the phonon-mediated control of magnetism in FePS₃. Moreover, we demonstrate coherent switching on and off of the metastable state, enabling applications such as high-performance magnetic storage.