International Workshop on Electronic Crystals
ECRYS-99

J. Phys. IV France 09 (1999) Pr10-133-Pr10-137
DOI: 10.1051/jp4:19991034

Space- and time-resolved X-ray diffraction from pinned and sliding charge-density-waves in NbSe₃

H. Requardt^{1, 2, 3}, F.Ya. Nad^{2, 4}, P. Monceau², R. Currat³, J . E. Lorenzo⁵, D. Rideau^{2, 3}, D. Smilgies⁶ and G. Grübel<sup>6

1</sup>  MPI f. Metallforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany
²  CRTBT, CNRS, BP. 166, 38042 Grenoble, France
³  Institut Laue Langevin, BP. 156, 38042 Grenoble, France
⁴  Institute of Radio-Engineering and Electronics, 103907 Moscow, Russia
⁵  Laboratoire de Cristallographie, CNRS, BP. 166, 38042 Grenoble, France
⁶  ESRF, BP. 220, 38043 Grenoble, France

Abstract
We have determined the spatial distribution of the local charge-density-wave (CDW) strain in the sliding state of NbSe₃. The strain is measured by monitoring the spatially-varying shift q(x) of the CDW satellite wave vector between current contacts. Experiments were carried out at T = 90 K in the upper CDW state using high spatial resolution (30-50 µm) X-ray diffraction. Applying direct currents about twice the threshold value, we observe a steep exponential decrease of the shift within a few hundred microns from the contact followed by a linear variation of q in the central section of the sample. This latter regime is attributed to transverse pinning of the CDW dislocation loops (DL), while the exponential regime is controlled by the finite DL nucleation rate. Additional to these data in the stationary state of the sliding CDW, we investigated the relaxation of the CDW strain q(t) upon switching off the current (T = 75 K). Using time-resolved high-spatial resolution X-ray diffraction, we observe at 800 µm from the electrode a decay law of the stretched exponential type : q(t) = q_oexp(-(t/τ)^µ) , with τ = 283 ms and µ = 0.37.

© EDP Sciences 1999