In-Plane Optical Anisotropy in a MoSe2/Au (110) Moiré Superstructure

In this work, we report the observation of the in-plane optical anisotropy in MoSe2/Au (110) moiré superstructure using reflectance difference spectroscopy, which is formed during the molecular beam epitaxy growth of monolayer MoSe2 on the Au (110) substrate. The MoSe2 moiré superstructure is examined with low-temperature scanning tunneling microscopy and further confirmed by the manifest of the break of C3v symmetry of free-standing MoSe2 with low energy electron diffraction. Furthermore, the density functional theory calculations, which allow us to determine the interfacial structure, corresponding electronic structure, and optical response of the strained MoSe2 monolayer on Au (110), reveal that the experimentally observed optical anisotropy can be attributed to the anisotropic deformation of the MoSe2 lattice by interacting with the underlying Au (110). This work provides an effective strategy for tuning the electronic and optical properties of two-dimensional materials by interfacial interactions through their epitaxial growth on selected substrate surfaces.