Eur. Phys. J. B 26, 417-430 (2002)
https://doi.org/10.1140/epjb/e20020109

Slow relaxation experiments in disordered charge and spin density waves: collective dynamics of randomly distributed solitons

¹ Centre de Recherches sur les Très Basses Températures (CRTBT) (U.P.R. 5001 du CNRS, Laboratoire conventionné avec l'Université Joseph Fourier) , CNRS BP 166X, 38042 Grenoble Cedex, France
² Institute of Physics of the University, PO Box 304, 41001 Zagreb, Croatia

Corresponding author: ^a melin@polycnrs-gre.fr

Received: 12 December 2001
Published online: 15 April 2002

Abstract

We show that the dynamics of disordered charge density waves (CDWs) and spin density waves (SDWs) is a collective phenomenon. The very low temperature specific heat relaxation experiments are characterized by: (i) “interrupted” ageing (meaning that there is a maximal relaxation time); and (ii) a broad power-law spectrum of relaxation times which is the signature of a collective phenomenon. We propose a random energy model that can reproduce these two observations and from which it is possible to obtain an estimate of the glass cross-over temperature (typically  mK). The broad relaxation time spectrum can also be obtained from the solutions of two microscopic models involving randomly distributed solitons. The collective behavior is similar to domain growth dynamics in the presence of disorder and can be described by the dynamical renormalization group that was proposed recently for the one dimensional random field Ising model [D.S. Fisher, P. Le Doussal, C. Monthus, Phys. Rev. Lett. 80, 3539 (1998)]. The typical relaxation time scales like . The glass cross-over temperature T_g related to correlations among solitons is equal to the average energy barrier and scales like . x is the concentration of defects, the correlation length of the CDW or SDW and Δ the charge or spin gap.