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

We report the investigations of specific heat, thermal conductivity, as well as thermoelectric power on the charge-density-wave (CDW) compound Lu5Ir4Si10 as a function of temperature. All thermal measurements consistently exhibit anomalous features around the CDW transition temperature T(o)similar to 80 K. Although the observations can be associated with the CDW formation, the measured anomalies are significantly large, in contrast to those in weak-coupled CDW materials. A quantitative analysis for the specific-heat data 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 gamma*/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. Besides, the observed giant excess specific heat DeltaC(p)/C(p)similar to 26% and thermal conductivity Delta kappa/kappa similar to 15% at T-o further support this strong-coupling scenario. These large enhancements in C-p and kappa are attributed to the results of substantially thermal excitation and heat carried by the soft phonons at the transition. In addition, a rapid change 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.