Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 99: 2D materials beyond graphene: TMDCs, silicene and relatives IV
O 99.7: Talk
Thursday, March 15, 2018, 16:45–17:00, MA 043
Characterization of Collective Ground States in Single-layer NbSe2 — •Miguel M. Ugeda1,2,3, Aaron J. Bradley1, Yi Zhang4, Seita Onishi1, Claudia Ojeda-Aristizabal1, Hyejin Ryu4, Alexander Riss1, Sung-Kwan Mo4, Dunghai Lee1, Alex Zettl1,5, Zahid Hussain4, Zhi-Xun Shen6,7, and Michael F. Crommie1,5 — 1Department of Physics, University of California at Berkeley, Berkeley, California, USA. — 2CIC nanoGUNE, Donostia-San Sebastian, Spain. — 3Ikerbasque, Basque Foundation for Science, Bilbao, Spain. — 4Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA. — 5Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA. — 6Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California, USA. — 7Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, California, USA.
In bulk NbSe2 a CDW sets in at 33K and superconductivity at 7.2K and their microscopic formation mechanisms remain controversial. In this talk I will present the electronic characterization of a single layer of NbSe2 by means of STM/STS, ARPES, and transport measurements (1,2). I will show that 3x3 CDW order in NbSe2 remains intact in 2D. Superconductivity also still remains in 2D, but its onset temperature is depressed to 1.9K. Our STS measurements reveal a CDW gap of 4 meV at EF, which is accessible due to the removal of bands crossing EF for a monolayer. [1] Ugeda, Nature Physics 12, 92 (2016). [2]Onishi, PSS B 253, 2396 (2016).