Paper 2D+MI-MoA9
Electronic Structure of Metallic Twin Grain Boundaries in Monolayer MoSe₂

Monday, November 7, 2016, 4:20 pm, Room 103B

Monolayers of MoSe₂ grown by molecular beam epitaxy on van der Waals substrates (HOPG or MoS₂), may exhibit twin grain boundaries. These Se-deficient line defects have been predicted by DFT to be metallic with dispersing bands. We examine their structural and electronic properties by scanning tunneling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES). A dispersing parabolic band is observed that intersects the Fermi-level indicating the metallic property of this defect. Below 235 K the line defect undergoes a Peierls, or charge density wave (CDW), transition. STM indicates a periodicity of 3 lattice constants of the CDW consistent with the Fermi-wavevector determined in ARPES. In addition, we determine that the defect behaves like an ideal one-dimensional metal. More specifically we show evidence of Tomonaga Luttinger liquid suppression of the density of states at the Fermi-level and the splitting of the band in a ‘spinon’ and ‘holon’ band, also known as spin-charge separation.