Molecular beam epitaxy growth of monolayer hexagonal MnTe2 on Si(111) substrate*

Monolayer MnTe 2 stabilized as 1T structure has been theoretically predicted to be a two-dimensional (2D) ferromagnetic metal and can be tuned via strain engineering. There is no naturally van der Waals (vdW) layered MnTe 2 bulk, leaving mechanical exfoliation impossible to prepare monolayer MnTe 2 . Herein, by means of molecular beam epitaxy (MBE), we successfully prepared monolayer hexagonal MnTe 2 on Si(111) under Te rich condition. Sharp reflection high-energy electron diffraction (RHEED) and low-energy electron diffraction (LEED) patterns suggest the monolayer is atomically flat without surface reconstruction. The valence state of Mn 4+ and the atom ratio of ([Te]:[Mn]) further confirm the MnTe 2 compound. Scanning tunneling spectroscopy (STS) shows the hexagonal MnTe 2 monolayer is a semiconductor with a large bandgap of ∼ 2.78 eV. The valence-band maximum (VBM) locates at the Γ point, as illustrated by angle-resolved photoemission spectroscopy (ARPES), below which three hole-type bands with parabolic dispersion can be identified. The successful synthesis of monolayer MnTe 2 film provides a new platform to investigate the 2D magnetism.