Magnetic Properties of Hexagonal FeX (X= Se, Te, S) Synthesized via Chemical Vapor Deposition

Two-dimensional (2D) iron-based monochalcogenides, such as FeS, FeSe, and FeTe, can crystallize in a hexagonal or tetragonal structure. While previous research mainly focused on the superconducting tetragonal FeSe and FeS, the magnetically ordered hexagonal phases have been less explored. Here, we synthesized hexagonal FeSe, FeS, and FeTe thin films on c-plane sapphire substrates using chemical vapor deposition (CVD). We used optical microscopy, atomic force microscopy, and Raman spectroscopy for structural characterization, and evaluated magnetic properties with a superconducting quantum interference device and nitrogen-vacancy magnetometry. Notably, both FeSe and FeS were ferromagnetic with a Curie temperature above room temperature. Hence, our study shows that CVD provides a cost-effective and reproducible route to the growth of 2D hexagonal iron chalcogenide thin films with tunable structure phases, enabling exploration of their magnetic properties.