On the transport and thermodynamic properties of quasi-two-dimensional purple bronzes A$_{0.9}$Mo$_6$O$_{17}$ (A=Na, K)

TL;DR

This study compares the transport and thermodynamic properties of quasi-two-dimensional purple bronzes Na$_{0.9}$Mo$_6$O$_{17}$ and K$_{0.9}$Mo$_6$O$_{17}$, focusing on their behavior near charge-density-wave transition temperatures and the role of disorder and phason excitations.

Contribution

It provides a comparative analysis of the specific heat, resistivity, and thermal conductivity of these bronzes, highlighting the influence of disorder and phason excitations on their properties.

Findings

Distinct behavior near charge-density-wave transition temperatures.

Enhanced thermal conductivity above $T_P$ linked to phason excitations.

Differences in disorder levels affect transport and thermodynamic responses.

Abstract

We report a comparative study of the specific heat, electrical resistivity and thermal conductivity of the quasi-two-dimensional purple bronzes Na$_{0.9}$Mo$_6$O$_{17}$ and K$_{0.9}$Mo$_6$O$_{17}$, with special emphasis on the behavior near their respective charge-density-wave transition temperatures $T_P$. The contrasting behavior of both the transport and the thermodynamic properties near $T_P$ is argued to arise predominantly from the different levels of intrinsic disorder in the two systems. A significant proportion of the enhancement of the thermal conductivity above $T_P$ in Na$_{0.9}$Mo$_6$O$_{17}$, and to a lesser extent in K$_{0.9}$Mo$_6$O$_{17}$, is attributed to the emergence of phason excitations.