Scanning Tunneling Microscopy of Novel Two-dimensional Magnetic Materials

The first part addresses previously unknown single-layer transition-metal chalcogenides. It introduces Cr₂S₃-2D, a newly identified two-dimensional chromium sulfide that has been established as the first single-layer A-type antiferromagnet, and discusses the observation of Néel vector switching using spin-polarized scanning tunneling microscopy [1-2]. It then turns to hexagonal Fe₂S₂, a newly identified single-layer iron sulfide polymorph, which hosts non-collinear antiferromagnetic states, including a 120° Néel state and a 2Q spin spiral.
The second part focuses on single-layer MnBr₂, where the interplay between epitaxy and interface effects gives rise to a long-wavelength super-moiré and substrate-dependent polaron formation [3-4]. Together, these results show how epitaxial growth and scanning tunneling microscopy can reveal previously unknown two-dimensional materials and uncover emergent magnetic order and electronic states in the single-layer limit.

References
[1] Safeer, A., et al. "Which Chromium–Sulfur Compounds Exist as 2D Material?." Advanced Functional Materials 35.49 (2025): e00907.
[2] Safeer, A., et al. "Atomic-Scale Detection of Néel Vector Switching in the Single-Layer A-type Antiferromagnet Cr2S3-2D." arXiv preprint arXiv:2604.07245 (2026).
[3] Safeer, A., et al. "MnBr₂ on the Graphene on Ir (110) Substrate: Growth, Structure, and Super-Moiré." Small (2026): e09471.
[4] Safeer, A., et al. "Substrate Role in Polaron Formation on Single-layer Transition Metal Dihalides." arXiv preprint arXiv:2512.21163 (2025).