CrSBr（Chromium Sulfur Bromide）

Chromium sulfide bromide (CrSBr) is an emerging two-dimensional (2D) van der Waals magnetic semiconductor that has attracted growing attention for its unique magnetic, electronic, and optical properties. It crystallizes in an orthorhombic structure with the space group Pmmn (No. 59). The crystal consists of alternately stacked Cr–S–Br layers, where each Cr atom is octahedrally coordinated by surrounding S and Br atoms through strong covalent bonding. The layers are held together by weak van der Waals interactions, allowing the material to be exfoliated into atomically thin sheets.

Magnetically, CrSBr is an anisotropic antiferromagnet. Bulk CrSBr exhibits interlayer antiferromagnetic couplingbelow its Néel temperature of approximately 132 K, while the spins within each layer are aligned ferromagnetically. Owing to its relatively weak interlayer coupling, its magnetic order can be effectively tuned by magnetic field, strain, or carrier doping, enabling magnetic phase transitions and spin reorientation.

In terms of electronic structure, CrSBr is an indirect bandgap semiconductor with a bandgap of about 1.5–1.8 eV, depending on thickness and strain. Its optical absorption covers the visible-light range, and it exhibits robust photoresponse and environmental stability. Unlike other chromium halides such as CrI₃ or CrCl₃, CrSBr is chemically stable in air, making it one of the few air-stable 2D magnetic materials known to date.

Thanks to its stable layered structure, tunable magnetism, and semiconducting nature, CrSBr holds great promise for applications in spintronics, magneto-optical devices, optoelectronics, and 2D magnetic heterostructures.