Quasi-one-dimensional metallic band dispersion in the commensurate charge density wave of 1T-TaS_2

摘要

The commensurate charge-density wave (CDW) in the layered compound 1T-TaS_2 has hitherto mostly been treated as a quasi-two-dimensional phenomenon. Recent band structure calculations have, however, predicted that the CDW coexists with a nearly one-dimensional metallic dispersion perpendicular to the crystal planes. Using synchrotron radiation-based angle-resolved photoemission spectroscopy, we show that this metallic band does in fact exist. Its occupied band width is in excellent agreement with predictions for a simple τ_c stacking order of the CDW between adjacent layers, and its periodicity in the c direction is 2π/c.