Aging effects and nonexponential energy relaxations in charge-density-wave systems

Low-energy excitations between charge-density-wave metastable states are revealed in low-temperature specific-heat measurements in quasi-one-dimensional materials as an excess contribution (to the lattice one) following a ${\mathrm{C}}_{\mathrm{p}}$=${\mathrm{T}}^{\nu }$ law with ν<1. In the same temperature range the energy relaxation is not exponential but follows a stretched exponential variation. Aging effects are also demonstrated. Analogies and differences with other glassy materials are briefly discussed.