  Manganese telluride (MnTe) has garnered strong interest recently for its
antiferromagnetic semiconductor properties, which are promising for
applications in spintronics, data storage, and quantum computing. In this
study, we discovered that the deposition of FeTe at 300oC onto zinc-blende MnTe
(ZB-MnTe) via molecular beam epitaxy (MBE) results in a phase transition from
ZB-MnTe to a layered MnTe (l-MnTe) phase with van der Waals (vdW) gaps, which
is a previously unreported phase of MnTe. The l-MnTe phase was characterized
using cross-sectional high-angle annular dark-field (HAADF) imaging,
energy-dispersive X-ray spectroscopy (EDS) mapping, and X-ray photoelectron
spectroscopy (XPS). The Fe/Te flux ratio during FeTe deposition was found to be
critical to the phase transition, an increased Fe/Te flux ratio used for the
FeTe growth leads to localized formation of layered Mn4Te3 (l-Mn4Te3), while a
decreased Fe/Te flux ratio only generates a single monolayer of l-MnTe at the
interface and the rest turns into a distorted ZB-MnTe (dZB-MnTe) phase. It was
also found that FT-MT heterostructures grown at a lower substrate temperature
of 250oC, as the Fe/Te flux ratio decreases, the ZB-MnTe layer was first
transformed to dZB-MnTe and then to wurtzite MnTe (WZ-MnTe). The FeTe/l-MnTe
heterostructure exhibits high-quality superconducting properties with a
three-dimensional nature as demonstrated by its magneto-transport properties
and there is evidence that l-MnTe seems to play a key role in inducing the
observed superconductivity. Most importantly, this study reports the
realization of layered structures of MnTe by an in-situ approach via chemical
interactions, which might be further applied to generating unprecedented phases
of materials under certain conditions.
