Anomalous specific heat peak of BaVS${}_3$ at 69 K explained by enhanced electron scattering upon ion relocation

Abstract

The present study deals with the anomalous heat capacity peak and thermal conductivity of BaVS${}_3$ near the metal-insulator transition present at $69$ K. The transition is related to a structural transition from an orthorhombic to monoclinic phase. Heat capacity measurements at this temperature exhibit a significant and relatively broad peak, which is also sample dependent. The present study calculates the entropy increase during the structural transition and we show that the additional entropy is caused by enhanced electron scattering as a result of the structural reorientation of the nuclei. Within the model it is possible to explain quantitatively the observed peak alike structure in the heat capacity and in heat conductivity.