| AVS 63rd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Thursday Sessions |
| Session 2D+MI-ThM |
| Session: | Properties of 2D Materials including Electronic, Magnetic, Optical, Mechanical, Thermal Properties |
| Presenter: | Miguel M. Ugeda, CIC nanoGUNE, Spain |
| Authors: | M.M. Ugeda, CIC nanoGUNE, Spain A.J. Bradley, University of California at Berkeley Y. Zhang, Advanced Light Source, Lawrence Berkeley National Laboratory S. Onishi, University of California at Berkeley W. Ruan, University of California at Berkeley Y. Chen, University of California at Berkeley C. Ojeda-Aristizabal, University of California at Berkeley H. Ryu, Advanced Light Source, Lawrence Berkeley National Laboratory M.T. Edmonds, University of California at Berkeley H.Z. Tsai, University of California at Berkeley A. Riss, University of California at Berkeley S.K. Mo, Advanced Light Source, Lawrence Berkeley National Laboratory D. Lee, University of California at Berkeley A. Zettl, University of California at Berkeley Z. Hussain, Advanced Light Source, Lawrence Berkeley National Laboratory Z.X. Shen, Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory M.F. Crommie, University of California at Berkeley |
| Correspondent: | Click to Email |
Layered transition metal dichalcogenides (TMDs) are ideal systems for exploring the effects of dimensionality on correlated electronic phases such as charge density wave (CDW) order and superconductivity. In bulk NbSe2 a CDW sets in at TCDW = 33 K and superconductivity sets in at Tc = 7.2 K. Below Tc these electronic states coexist but their microscopic formation mechanisms remain controversial. In this tal I will present the electronic characterization study of a single 2D layer of NbSe2 by means of low temperature scanning tunneling microscopy/spectroscopy (STM/STS), angle-resolved photoemission spectroscopy (ARPES), and electrical transport measurements (1). I will show that 3x3 CDW order in NbSe2 remains intact in 2D. Superconductivity also still remains in the 2D limit, but its onset temperature is depressed to 1.9 K. Our STS measurements at 5 K reveal a CDW gap of Δ = 4 meV at the Fermi energy, which is accessible via STS due to the removal of bands crossing the Fermi level for a single layer. Our observations are consistent with the simplified (compared to bulk) electronic structure of single-layer NbSe2, thus providing insight into CDW formation and superconductivity in this model strongly-correlated system. Furthermore I will show that CDW order is also present in 2D semiconducting TMDs around 1D mirror twin boundaries (2).
(1) M. M. Ugeda, et al., Nature Physics 12, 92 (2016).
(2) S. Barja, et al., Nature Physics, in press (2016).