Superconducting Properties of the K$_{{x}}$WO$_{3}$ Tetragonal Tungsten Bronze and the Superconducting Phase Diagram of the Tungsten Bronze Family

摘要

We report the superconducting properties of the K$_{x}$WO$_{3}$ tetragonaltungsten bronze. The highest superconducting transition temperature($T_{c}=2.1$K) was obtained for K$_{0.38}$WO$_{3}$. $T_{c}$ decreases linearlywith increasing K content. Using the measured values for the upper criticalfield $H_{c2}$, and the specific heat $C$, we estimate the orbital criticalfield $H_{c2}$(0), coherence length $\xi$(0), Debye temperature $\Theta _{D}$and coupling constant $\lambda _{ep}$. The magnitude of the specific heat jumpat $T_{c}$ suggests that the K$_{x}$WO$_{3}$ tetragonal tungsten bronze is aweakly-coupled superconductor. The superconducting phase diagram of the dopedtungsten bronze family is presented.