Variable temperature scanning tunneling microscopy studies of the charge density wave phases in tantalum disulfide

Variable temperature scanning tunneling microscopy has been used to elucidate details of the nearly commensurate charge density wave (CDW) phase in 1T-TaS2. Large-area images show that the nearly commensurate phase has a hexagonal domain structure, and that the domain period exhibits a strong temperature dependence. Real-space and two-dimensional Fourier transform analyses of atomic resolution images further demonstrate that within the domains the CDW is approximately commensurate with the atomic lattice, and that between domains the CDW amplitude decreases and the CDW phase changes. In addition, disorder observed in the hexagonal domain structure at low temperatures is suggested to be due to domain wall pinning.