Alternative model for the structural modulation in NbSe3 and m-TaS3 -: art. no. 115423

A model is proposed for the sliding charge density wave mechanism in the isostructural quasi-one-dimensional compounds NbSe3 and m-TaS3. It is based on an assumption that below either of the two onset temperatures T-1 and T-2 both modulation modes are present and form small statistically distributed domains along particular trigonal prismatic columns, i.e., along type III below T-1 and in addition along type I below T-2. Presuming the domains are of comparable sizes to the coherence lengths in the diffraction experiments, their disordered distribution results in a selective contribution to the reciprocal space in both temperature regions, which is in good accord with the diffraction experiments. The model might form the basis for a better explanation of the twinkling domains and low temperature tunneling microscopic images, which were not fully understood on basis of the old model with a selective occupation of the two column types by the two modulation modes.