On the origin of the anomalous peak in the resistivity of TiSe$_2$

Abstract

Resistivity measurements of TiSe$_2$ typically show only a weak change in gradient at the charge density wave transition at $T_{CDW}\approx$ 200~K, but more prominently feature a broad peak at a lower $T_{peak}\sim$ 165~K, which has remained poorly understood despite decades of research on the material. Here we present quantitative simulations of the resistivity using a simplified parametrization of the normal state band structure, based on recent photoemission data. Our simulations reproduce the overall profile of the resistivity of TiSe$_2$, including its prominent peak, without implementing the CDW at all. We find that the peak in resistivity corresponds to a crossover between a low temperature regime with electron-like carriers only, to a regime around room temperature where thermally activated and highly mobile hole-like carriers dominate the conductivity. Even when implementing substantial modifications to model the CDW below the transition temperature, we find that these thermal population effects still dominate the transport properties of TiSe$_2$.