Finite-length charge-density waves on terminated atomic wires

Abstract

Finite-size effects in charge-density waves (CDWs) were unveiled using scanning tunneling microscopy for metallic atomic wires on the Au/Si(553) surface, as terminated by adsorbate impurities. We found that CDW formed at low temperature adopts the finite-length boundary condition in two distinct ways, depending on the length scale. For longer wires than $\ensuremath{\sim}$10 nm, the CDW correlation length, the decay length of the CDW amplitude from the terminating ends, scales continuously with the wire length as predicted in a recent hyperscaling theory [Phys. Rev. B 75, 205428 (2007)]. For shorter wires, the boundary condition becomes discrete with respect to the CDW wavelength of 3${a}_{0}$. For incommensurate wire lengths with 3${a}_{0}$, fluctuating CDW states were observed, which are due to the motion of solitonlike antiphase boundaries.