Molecular beam epitaxy growth of iodide thin films*

Abstract

Study of two-dimensional (2D) magnetic materials is important for both fundamental research and application. Here we report molecular beam epitaxy growth of iodides, candidates for exhibiting 2D magnetism. Decomposition of CrI3 is utilized to produce stable gaseous I2 flux. Growth of MnI2, GdI3, and CrI2 down to monolayer is successful achieved by co-depositing I2 and corresponding metal atoms. The thin films of the three materials are characterized by scanning tunneling microscope and found to be insulators with bandgaps of 4.4 eV, 0.6 eV, and 3.0 eV, respectively. The film growth paves the way for further study of magnetic properties at the 2D limit.