Suppression of anomalous phonon scattering via Zn substitution in the metallic phase of Cu1-xZnxIr2S4

Abstract

We investigate herein the thermal transport properties of Cu1-xZnxIr2S4 (0 ≤ x ≤ 0.3). The thermal conductivity of CuIr2S4 exhibits an abrupt change during the metal-insulator transition (MIT). This change is attributed to a 59% decrease in phonon thermal conductivity κph from the insulating phase to the metallic phase (MP). Specifically, a κph of x = 0.05 and 0.1 shows a decrease at the MIT temperature. However, the decrease at the MIT temperature reduces with an increase in the Zn substitution. At x = 0.3, the MIT is almost suppressed. The decrease in κph is attributed to a significant decrease in the phonon mean free path l, suggesting that anomalous phonon scattering is introduced additionally in the MP. Furthermore, l in the MP increases with increasing Zn substitution from x = 0.05 to 0.3, and this suggests that the anomalous phonon scattering in the MP is suppressed by Zn substitution.