Two channel heat conduction in the superconducting state of the as-cast V$_{1-x}$Zr$_x$ alloys

TL;DR

This study investigates heat capacity and thermal conductivity in V$_{1-x}$Zr$_x$ alloys, revealing multiple superconducting phases and enhanced thermal conductivity due to phase coexistence in the superconducting state.

Contribution

It provides the first detailed analysis of two-channel heat conduction in the superconducting state of V$_{1-x}$Zr$_x$ alloys, linking phase coexistence to thermal transport.

Findings

Identification of three superconducting phases with distinct transition temperatures.

Observation of higher-than-expected thermal conductivity in the superconducting state.

Evidence of two parallel channels for heat conduction due to phase coexistence.

Abstract

We present here the temperature dependence of heat capacity ($C$($T$)) and thermal conductivity ($\kappa$($T$)) in the superconducting state as well as in the normal state of as-cast V$_{1-x}$Zr$_x$ alloys. Distinct jumps in the $C$($T$) of the alloys indicate the presence of three superconducting phases with transition temperatures $T_{C1}$ = 5.4~K, $T_{C2}$ = 8.2~K and $T_{C3}$ = 8.5~K. From the metallography micrographs, these three phases are identified to be $\beta$-V, $\gamma$-ZrV$_2$, and $\gamma'$-ZrV$_2$ respectively. Apart from these phases, $\alpha$-Zr and $\beta$-Zr phases are also detected in these samples. The experimental $\kappa$($T$) in the superconducting state of these alloys is observed to be significantly higher than that expected theoretically. Our analysis suggests that the above observation is due to the coexistence of multiple superconducting and non superconducting phases which resulted in the two-parallel channels for the conduction of heat.