title: Discovery of an Unconventional Charge Density Wave at the Surface of K_{0.9}Mo_{6}O_{17}.
abstract: We use angle resolved photoemission spectroscopy, Raman spectroscopy, low energy electron diffraction, and x-ray scattering to reveal an unusual electronically mediated charge density wave (CDW) in K_{0.9}Mo_{6}O_{17}. Not only does K_{0.9}Mo_{6}O_{17} lack signatures of electron-phonon coupling, but it also hosts an extraordinary surface CDW, with T_{S_CDW}=220  K nearly twice that of the bulk CDW, T_{B_CDW}=115  K. While the bulk CDW has a BCS-like gap of 12 meV, the surface gap is 10 times larger and well in the strong coupling regime. Strong coupling behavior combined with the absence of signatures of strong electron-phonon coupling indicates that the CDW is likely mediated by electronic interactions enhanced by low dimensionality.
authors.affiliation: Division of Materials Science and Engineering, Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.|Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Daixiang
authors.initials: D
authors.lastname: Mou
authors.affiliation: Division of Materials Science and Engineering, Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.|Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: A
authors.initials: A
authors.lastname: Sapkota
authors.affiliation: Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: H-H
authors.initials: HH
authors.lastname: Kung
authors.affiliation: Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Viktor
authors.initials: V
authors.lastname: Krapivin
authors.affiliation: Division of Materials Science and Engineering, Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.|Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Division of Materials Science and Engineering, Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.|Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: A
authors.initials: A
authors.lastname: Kreyssig
authors.affiliation: National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Xingjiang
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Division of Materials Science and Engineering, Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.|Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: A I
authors.initials: AI
authors.lastname: Goldman
authors.affiliation: Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.|National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia.
authors.forename: G
authors.initials: G
authors.lastname: Blumberg
authors.affiliation: Division of Materials Science and Engineering, Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.|Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Flint
authors.affiliation: Division of Materials Science and Engineering, Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.|Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Kaminski