Spatial structure formation in charge density wave systems

Besides the superlattice with the period equal to twice the Fermi wave vector q=2kF, charge density waves (CDW) also show a spatial structure formation with a length scale much larger than the period of the superlattice. Following the theory of Fukuyama, Lee, and Rice (FLR), values of some microns are expected for the extension of the FLR domains. We have performed investigations with a low-temperature scanning electron microscope (SEM) on K0.30MoO3 and TaS3, in order to visualize these domain-like structures. In contrast to the usual SEM methods, we recorded the electric response (e.g., the thermovoltage) of the sample in dependence of the beam position. The analysis of the images obtained reveals values for different parameters that well agree with the ones obtained by other methods.