Direct Imaging of Antiferromagnet-Ferromagnet Phase Transition in Van Der Waals Antiferromagnet CrSBr

The advent of van der Waals (vdW) ferromagnetic (FM) and antiferromagnetic (AFM) materials offers unprecedented opportunities for spintronics and magneto-optic devices. Combining magnetic Kerr microscopy and density functional theory calculations, the AFM-FM transition is investigated and a surprising abnormal magneto-optic anisotropy in vdW CrSBr associated with different magnetic phases (FM, AFM, or paramagnetic state) is discovered. This unique magneto-optic property leads to different anisotropic optical reflectivity from different magnetic states, permitting direct imaging of the AFM Neel vector orientation and the dynamic process of the AFM-FM transition within a magnetic field. Using Kerr microscopy, not only the domain nucleation and propagation process is imaged but also the intermediate spin-flop state in the AFM-FM transition is identified. The unique magneto-optic property and clear identification of the dynamics process of the AFM-FM phase transition in CrSBr demonstrate the promise of vdW magnetic materials for future spintronic technology. Combining magnetic Kerr microscopy and density functional theory calculations, a successful imaging of antiferromagnetic-ferromagnetic (AFM-FM) phase transition in van der Waals (vdW) AFM CrSBr based on its unique magneto-optic property is demonstrated. These findings reveal enormous prospects for magnetism imaging and control in 2D spintronics with vdW AFM.image