Novel Mechanism of a Charge Density Wave in a Transition Metal Dichalcogenide

Department of Physics, Applied Surface Physics State Key Laboratory, Fudan University, Shanghai 200433, China.
Physical Review Letters (Impact Factor: 7.51). 12/2007; 99(21):216404. DOI: 10.1103/PhysRevLett.99.216404
Source: PubMed

ABSTRACT The charge density wave (CDW) is usually associated with Fermi surfaces nesting. We here report a new CDW mechanism discovered in a 2H-structured transition metal dichalcogenide, where the two essential ingredients of the CDW are realized in very anomalous ways due to the strong-coupling nature of the electronic structure. Namely, the CDW gap is only partially open, and charge density wave vector match is fulfilled through participation of states of the large Fermi patch, while the straight Fermi surface sections have secondary or negligible contributions.

Download full-text


Available from: D. H. Lu, Mar 24, 2015
24 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The electronic structure of a new charge-density-wave/ superconductor system, 1T-CuxTiSe2, has been studied by photoemission spectroscopy. A correlated semiconductor band structure is revealed for the undoped case. With Cu doping, the charge density wave is suppressed by the raising of the chemical potential, while the superconductivity is enhanced by the enhancement of the density of states. Moreover, the strong scattering at high doping might be responsible for the suppression of superconductivity in that regime. Comment: 5 pages, 4 figures
    Physical Review Letters 12/2006; 99(14). DOI:10.1103/PhysRevLett.99.146401 · 7.51 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report an optical study of transition metal dichalcogenide 2H-TaS2 and the Na intercalated superconductor NaxTaS2 over a broad frequency range at various temperatures. A clear gap feature was observed for 2H-TaS2 when it undergoes the charge-density wave (CDW) transition. The existence of a Drude component in sigma1(omega) below TCDW indicates that the Fermi surface of 2H-TaS2 is only partially gapped in the CDW state. The spectral evolution of two different NaxTaS2 crystals further confirms that the partial gap structure observed in 2H-TaS2 has a CDW origin. The CDW mechanism for 2H-TaS2 and the competition between CDW and superconductivity in the NaxTaS2 system are discussed.
    Physical review. B, Condensed matter 07/2007; 76(4). DOI:10.1103/PhysRevB.76.045103 · 3.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: NbSe2 is a prototypical charge-density-wave (CDW) material, whose mechanism remains mysterious so far. With angle resolved photoemission spectroscopy, we recovered the long-lost nesting condition over a large broken-honeycomb region in the Brillouin zone, which consists of six saddle band point regions with high density of states (DOS), and large regions away from Fermi surfaces with negligible DOS at the Fermi energy. We show that the major contributions to the CDW formation come from these barely occupied states rather than the saddle band points. Our findings not only resolve a long-standing puzzle, but also overthrow the conventional wisdom that CDW is dominated by regions with high DOS.
    Physical Review Letters 11/2008; 101(22):226406. DOI:10.1103/PhysRevLett.101.226406 · 7.51 Impact Factor
Show more