Portal de Periódicos da CAPES

Coexistence of Gapless Excitations and Commensurate Charge-Density Wave in the 2 H Transition Metal Dichalcogenides

2006; American Physical Society; Volume: 96; Issue: 2 Linguagem: Inglês

10.1103/physrevlett.96.026406

1092-0145

Ryan Barnett, Anatoli Polkovnikov, Eugene Demler, Wei‐Guo Yin, Wei Ku,

Advanced Chemical Physics Studies

An unexpected feature common to $2H$ transition metal dichalcogenides ($2H$ TMDs) is revealed with a first-principles Wannier function analysis of the electronic structure of the prototype $2H$ ${\mathrm{TaSe}}_{2}$: The low-energy Ta ``$5{d}_{{z}^{2}}$'' bands governing the physics of a charge-density wave (CDW) is dominated by hopping between next-nearest neighbors. With this motivation we develop a minimal effective model for the CDW formation, in which the unusual form of the hopping leads to an approximate decoupling of the three sublattices. In the CDW phase one sublattice remains undistorted, leaving the bands associated with it ungapped everywhere in the Fermi surface, resolving the long-standing puzzle of the coexistence of gapless excitations and commensurate CDW in the $2H$ TMDs.