Thermal properties of Lu5Ir4Si10 near the charge-density-wave transition -art. no. 125124

We report the investigations of specific heat, thermal conductivity, as wel l as thermoelectric power on the charge-density-wave (CDW) compound Lu5Ir4S i10 as a function of temperature. All thermal measurements consistently exh ibit anomalous features around the CDW transition temperature T(o)similar t o 80 K. Although the observations can be associated with the CDW formation, the measured anomalies are significantly large, in contrast to those in we ak-coupled CDW materials. A quantitative analysis for the specific-heat dat a near the fluctuation region yields a critical exponent alpha similar to2, much larger than the predicted value alpha =0.5 in the extended mean-field theory assuming three-dimensional fluctuations. We also obtained a ratio g amma*/gamma =8.4, a factor of 6 larger than the BCS value 1.43 in the weak- coupling limit, indicating a strong coupling of this phase transition. Besi des, the observed giant excess specific heat DeltaC(p)/C(p)similar to 26% a nd thermal conductivity Delta kappa/kappa similar to 15% at T-o further sup port this strong-coupling scenario. These large enhancements in C-p and kap pa are attributed to the results of substantially thermal excitation and he at carried by the soft phonons at the transition. In addition, a rapid chan ge in the sign of thermoelectric power at T-o was observed, which provides a better understanding of the evolution of electronic band structure of the system below and above the CDW formation.