Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 57: Focus Session: Many-body effects in two-dimensional materials
O 57.3: Talk
Wednesday, March 9, 2016, 10:15–10:30, H16
Observation of charge density wave order in 1D mirror twin boundaries of single-layer MoSe2 — •Sara Barja1, Sebastian Wickenburg1, Zhen-Fei Liu1, Yi Zhang1, Hyejin Ryu1, Miguel M. Ugeda2, Zahid Hussain1, Zhi-Xun Shen3, Sung-Kwan Mo1, Miquel B. Salmeron1,2, Feng Wang1,2, Michael F. Crommie1,2, D. Frank Ogletree1, Jeffrey B. Neaton1,2, and Alexander Weber-Bargioni1 — 1Lawrence Berkeley National Laboratory, Berkeley, CA, USA — 2University of California at Berkeley, Berkeley, CA, USA — 3Stanford Institute of Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
Detailed understanding of defect structure in 2D transition metal dichalcogenides may lead to control of the material properties. Here we provide direct evidence for the existence of isolated, 1D charge density waves (CDWs) at mirror twin boundaries (MTBs) in single-layer MoSe2. 4K-STM/STS measurements reveal a substantial bandgap of 60-140 meV opening at the Fermi level in the otherwise one dimensional metallic structure. We find an energy-dependent periodic modulation in the density of states along the MTB, with a wavelength of approximately three lattice constants. The modulations in the density of states above and below the Fermi level are spatially out of phase, consistent with CDW order. In addition to the electronic characterization, we determine the atomic structure and bonding configuration of the 1D MTB by means of high-resolution nc-AFM. DFT calculations reproduce both the gap opening and the modulations of the density of states.