Electronic Janus lattice and kagome-like bands in coloring-triangular MoTe2 monolayers

TL;DR

This paper reports the synthesis and characterization of a novel coloring-triangle lattice in MoTe2 monolayers, revealing Janus lattice features and Dirac-like bands, with potential applications in electronic devices.

Contribution

It introduces a new coloring-triangle lattice in MoTe2 monolayers with Janus lattice properties, achieved through controlled boundary engineering in molecular beam epitaxy.

Findings

Identification of electronic Janus lattice in MoTe2 monolayers.

Observation of Dirac-like and flat bands in the electronic structure.

Potential for energy-tunable electron-tunneling applications.

Abstract

Polymorphic structures of transition-metal dichalcogenides (TMDs) host exotic electronic states, like charge density wave and superconductivity. However, the number of these structures is limited by crystal symmetries, which poses a challenge to achieve tailored lattices and properties both theoretically and experimentally. Here, we report a coloring-triangle (CT) latticed MoTe2 monolayer, termed CT-MoTe2, constructed by controllably introducing uniform and ordered mirror-twin-boundaries into a pristine monolayer in molecular beam epitaxy. Low-temperature scanning tunneling microscopy and spectroscopy (STM/STS) together with theoretical calculations reveal that the monolayer has an electronic Janus lattice, i.e., an energy-dependent atomic-lattice and a pseudo-Te sublattice, and shares the identical geometry with the Mo5Te8 layer. Dirac-like and flat electronic bands inherently existing in the CT lattice are identified by two broad and two prominent peaks in STS spectra, respectively, and verified with density-functional-theory calculations. Two types of intrinsic domain boundaries were observed, in one of which the electronic-Janus-lattice feature maintains, implying potential applications as an energy-tunable electron-tunneling barrier in future functional devices.