New aspects of the QC-phase in layered 1T-TaS2

Abstract

Abstract We present Fermi surface (FS) mapping measurements obtained by photoemission for the quasi-commensurate charge density wave (CDW) phase of layered 1T-TaS2. The topology of the FS is rather dominated by the undistorted (1×1) symmetry than by the CDW-induced ( 13 × 13 ) phase. CDW effects can be seen in terms of nesting properties of the FS. Compared to one-electron band structure calculations we observe changed FS contours of Ta 5d-derived electron pockets around the M,M′ points of the (1×1) Brillouin zone. Low energy electron diffraction measurements support the view of a quasi-commensurate CDW.