Towards equilibrium ground state in charge-density-wave systems

We present a study of energy relaxation in two representative charge-density-wave compounds: ${\mathrm{TaS}}_3$ and ${\mathrm{NbSe}}_3$ below T=0.5 K. The evolution of the relaxation indicates a crossover between a nonequilibrium state and the thermodynamical equilibrium state when the system has been allowed to age. In the equilibrium state the relaxation is thermally activated with an activation energy of ∼1 K. We interpret these results as long-time dynamics in the network of charge-density-wave dislocations with a critical temperature close to 0 K.