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

Abstract

We present here the temperature dependence of heat capacity ($C$($T$)) and thermal conductivity ($κ$($T$)) 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 $β$-V, $γ$-ZrV$_2$, and $γ'$-ZrV$_2$ respectively. Apart from these phases, $α$-Zr and $β$-Zr phases are also detected in these samples. The experimental $κ$($T$) 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.