Topological Solitons versus Nonsolitonic Phase Defects in a Quasi-One-Dimensional Charge-Density Wave

We investigated phase defects in a quasi-one-dimensional commensurate charge-density wave (CDW) system, an In atomic wire array on Si(111), using low temperature scanning tunneling microscopy. The unique fourfold degeneracy of the CDW state leads to various phase defects, among which intrinsic solitons are clearly distinguished. The solitons exhibit a characteristic variation of the CDW amplitude with a coherence length of about 4 nm, as expected from the electronic structure, and a localized electronic state within the CDW gap. While most of the observed solitons are trapped by extrinsic defects, moving solitons are also identified and their novel interaction with extrinsic defects is disclosed. DOI: 10.1103/PhysRevLett.109.246802X1115sciescopu

Radial Band Structure of Electrons in Liquid Metals

The electronic band structure of a liquid metal was investigated by measuring precisely the evolution of angle-resolved photoelectron spectra during the melting of a Pb monolayer on a Si(111) surface. We found that the liquid monolayer exhibits a free-electron-like band and it undergoes a coherent radial scattering, imposed by the radial correlation of constituent atoms, to form a characteristic secondary hole band. This unique double radial bands and their gradual evolution during melting can be quantitatively reproduced, including detailed spectral intensity profiles, with our radial scattering model based on a theoretical prediction of 1962. Our result establishes the radial band structure as a key concept for describing the nature of electrons in strongly disordered states of matter.Comment: 4 pages, 4 figures, accepted to Physical Review Letter