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
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 Tg
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.
PACS: 05.70.Ln – Nonequilibrium and irreversible thermodynamics / 63.50.+x – Vibrational states in disordered systems / 75.30.Fv – Spin-density waves
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002