Deformation of charge density waves in quasi-one-dimensional semiconductors visualized by scanning electron microscopy

Abstract

It is well known that charge density wave systems exhibit a variety of phenomena related to the existence of metastable states: Electric measurements reveal hystereses in both their thermal and electric behavior as well as different kinds of memory effects. Although these integral methods provide strong evidence for metastability, they can not uncover the spatial structure of the charge density wave. As predicted by the theory of Fukuyama, Lee, and Rice, the charge density wave should organize in domains obeying a characteristic length scale. We have performed investigations on a TaS₃ sample with a low-temperature scanning electron microscope, using the electron beam as weak local heat source and recording the thermopower as a function of the beam position. We demonstrate that the structures observed can be related to metastable deformations of the charge density wave.