Insulator-to-metal Mott transition facilitated by lattice deformation in monolayer -RuCl3 on graphite

Creating heterostructures with graphene/graphite is a practical method for charge -doping alpha-RuCl3, but not sufficient to cause the insulator -to -metal transition. In this study, detailed scanning tunneling microscopy/spectroscopy measurements on alpha-RuCl3 with various lattice deformations reveal that both in -plane and out -of -plane lattice distortions may collapse the Mott gap in the case of monolayer alpha-RuCl3 in proximity to graphite, but have little impact on its bulk form alone. In the Mott -Hubbard framework, the transition is attributed to the lattice -distortion -facilitated substantial modulation of the electron correlation parameter. Observation of the orbital textures on a highly compressed monolayer alpha-RuCl3 flake on graphite provides valuable evidence that electrons are efficiently transferred from the heterointerface into Cl3p orbitals under the lattice distortion. It is believed that the splitting of Ru t2g bands within the trigonal distortion of Ru-Cl-Ru octahedra bonds generated the electrons' transfer pathways. The increase of the Cl3p states enhances the hopping integral in the Mott -Hubbard bands, resulting in the Mott transition. These findings suggest a different route for implementing the insulator -to -metal transition upon doping in alpha-RuCl3 by deforming the lattice in addition to the formation of the heterostructure.