Exploring Magnetism in Transition Metal Monochalcogenide Multilayer Films Synthesized via Chemical Vapor Deposition

Nonlayered materials such as FeX (X: Se, S, Te) are systems of current interest in fundamental scientific research studies. The tetragonal-FeSe (t-FeSe) has been synthesized via molecular beam epitaxy (MBE), chemical vapor deposition (CVD), among other methods. Consequently, the t-FeSe and its superconducting behavior has been extensively investigated. In addition, the tetragonal-FeTe (t-FeTe) has been synthesized and its antiferromagnetic nature studied a great deal. However, the hexagonal-FeSe has not been realized experimentally via CVD. Therefore, the hexagonal-FeSe is a system of current interest in the scientific community to explore its potential magnetic anisotropy and semiconducting behavior as predicted by density functional theory (DFT) studies. With this goal in mind, we set out to use CVD growth technique to synthesize hexagonal-FeSe multilayer films to investigate magnetism. Using bismuth oxychloride salt (BiOCl) as the promotor and Fe and Se powder as the precursors, we synthesized hexagonal-FeSe multilayers on C-plane sapphire substrates. The as-grown samples exhibit ferromagnetic order with a Curie temperature above room temperature. The ability to grow hexagonal-FeSe multilayers at the atomic scale via CVD opens the possibility of designing and synthesizing materials with engineered properties using a cost-effective and a high-throughput growth technique. This study provides a platform for the exploration of quantum phenomena such as topological superconductivity in low dimension materials.