title: Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H-NbSe2.
abstract: We show that a small number of intentionally introduced defects can be used as a spectroscopic tool to amplify quasiparticle interference in 2H-NbSe2 that we measure by scanning tunneling spectroscopic imaging. We show, from the momentum and energy dependence of the quasiparticle interference, that Fermi surface nesting is inconsequential to charge density wave formation in 2H-NbSe2. We demonstrate that, by combining quasiparticle interference data with additional knowledge of the quasiparticle band structure from angle resolved photoemission measurements, one can extract the wave vector and energy dependence of the important electronic scattering processes thereby obtaining direct information both about the fermiology and the interactions. In 2H-NbSe2, we use this combination to confirm that the important near-Fermi-surface electronic physics is dominated by the coupling of the quasiparticles to soft mode phonons at a wave vector different from the charge density wave ordering wave vector.
authors: Department of Physics, Columbia University, New York, New York 10027, USA.
authors: C J
authors: CJ
authors: Arguello
authors: Department of Physics, Columbia University, New York, New York 10027, USA.
authors: E P
authors: EP
authors: Rosenthal
authors: Department of Physics, Columbia University, New York, New York 10027, USA.
authors: E F
authors: EF
authors: Andrade
authors: Department of Applied Physics and Applied Math, Columbia University, New York, New York 10027, USA.
authors: W
authors: W
authors: Jin
authors: Department of Applied Physics and Applied Math, Columbia University, New York, New York 10027, USA.
authors: P C
authors: PC
authors: Yeh
authors: Department of Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors: N
authors: N
authors: Zaki
authors: Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA.
authors: S
authors: S
authors: Jia
authors: Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA.
authors: R J
authors: RJ
authors: Cava
authors: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors: R M
authors: RM
authors: Fernandes
authors: Department of Physics, Columbia University, New York, New York 10027, USA.
authors: A J
authors: AJ
authors: Millis
authors: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors: T
authors: T
authors: Valla
authors: Department of Electrical Engineering, Columbia University, New York, New York 10027, USA and Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA.
authors: R M
authors: RM
authors: Osgood
authors: Department of Physics, Columbia University, New York, New York 10027, USA.
authors: A N
authors: AN
authors: Pasupathy