Remnant Fermi Surface in the Presence of an Underlying Instability in Layered1T–TaS2

We report high resolution angle-scanned photoemission and Fermi surface (FS) mapping experiments on the layered transition-metal dichalcogenide $1T-{\mathrm{TaS}}_2$ in the quasicommensurate (metallic) and the commensurate (insulating) charge-density-wave (CDW) phase. Instead of a nesting induced partially removed FS in the CDW phase we find a pseudogap over large portions of the FS. This remnant FS exhibits the symmetry of the one-particle normal state FS. Possibly, this Mott localization induced transition represents the underlying instability responsible for the pseudogapped FS.