title: Direct observation of charge state in the quasi-one-dimensional conductor Li0.9Mo6O17.
abstract: The quasi-one-dimensional conductor Li0.9Mo6O17 has been of great interest because of its unusual properties. It has a conducting phase with properties different from a simple Fermi liquid, a poorly understood "insulating" phase as indicated by a metal-"insulator" crossover (a mystery for over 30 years), and a superconducting phase which may involve spin triplet Cooper pairs as a three-dimensional (p-wave) non-conventional superconductor. Recent evidence suggests a density wave (DW) gapping regarding the metal-"insulator" crossover. However, the nature of the DW, such as whether it is due to the change in the charge state or spin state, and its relationship to the dimensional crossover and to the spin triplet superconductivity, remains elusive. Here by performing (7)Li-/(95)Mo-nuclear magnetic resonance (NMR) spectroscopy, we directly observed the charge state which shows no signature of change in the electric field gradient (nuclear quadrupolar frequency) or in the distribution of it, thus providing direct experimental evidences demonstrating that the long mysterious metal-"insulator" crossover is not due to the charge density wave (CDW) that was thought, and the nature of the DW gapping is not CDW. This discovery opens a parallel path to the study of the electron spin state and its possible connections to other unusual properties.
authors: College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China.|Department of Physics, University of West Florida, Pensacola 32514, USA.|Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
authors: Guoqing
authors: G
authors: Wu
authors: College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China.
authors: Xiao-shan
authors: XS
authors: Ye
authors: College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China.
authors: Xianghua
authors: X
authors: Zeng
authors: Department of Math and Computer Science, Fayetteville State University, Fayetteville, North Carolina 28301, USA.
authors: Bing
authors: B
authors: Wu
authors: Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
authors: W G
authors: WG
authors: Clark