IMAGING THE SPATIAL STRUCTURE OF METASTABLE STATES IN A CHARGE-DENSITY-WAVE SYSTEM WITH THE SCANNING ELECTRON-MICROSCOPE

It is well known that charge density wave systems exhibit a variety of phenomena related to the existence of metastable states: Electric mea surements reveal hystereses in both their thermal and electric behavio r as well as different kinds of memory effects. Although these integra l methods provide strong Evidence for metastability, they can not unco ver 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 per formed investigations on a TaS3 sample with a low-temperature scanning electron microscope, using the electron beam as weak local heat sourc e and recording the thermopower as a function of the beam position. We demonstrate: that the structures observed can be related to metastabl e deformations of the charge density wave. (C) 1997 Elsevier Science B .V.