Spin-fluctuations in Ti$_{60}$V$_{40}$ alloy and its influence on the superconductivity

TL;DR

This study investigates spin-fluctuations in Ti$_{0.6}$V$_{0.4}$ alloy and their impact on superconductivity, revealing itinerant spin-fluctuations and possible preformed Cooper-pairs above the transition temperature.

Contribution

It provides experimental evidence of spin-fluctuations in Ti$_{0.6}$V$_{0.4}$ and analyzes their influence on superconducting properties, highlighting the widespread relevance of spin-fluctuations in superconductors.

Findings

Presence of T$^2$lnT behavior in magnetic susceptibility.

Resistivity follows T$^2$ behavior between 20-50 K.

Negative T$^5$ term indicates spin-fluctuations.

Abstract

We report experimental studies of the temperature and magnetic field dependence of resistivity and dc magnetic susceptibility and the temperature dependence of zero field heat capacity in a Ti$_{0.6}$V$_{0.4}$ alloy. The temperature dependence of the normal state dc magnetic susceptibility in this Ti$_{0.6}$V$_{0.4}$ alloy shows T$^2$lnT behavior. The temperature dependence of resistivity follows a T$^2$ behaviour in the range 20-50 K. On the other hand, a term $T^3$ lnT is needed in the expression containing the electronic and lattice heat capacities to explain the temperature dependence of heat capacity at temperatures where $T^2$ dependence of resistivity is observed. Such temperature dependence of dc magnetic susceptibility, resistivity and heat capacity are indications of the presence of spin-fluctuations in the system. Further experimental evidence for the spin fluctuations is obtained in the form of a negative value of T$^5$ term in the temperature dependence of resistivity. The influence of spin-fluctuations on the superconducting properties of Ti$_{0.6}$V$_{0.4}$ is discussed in detail. We show from our analysis of resistivity and the susceptibility in normal and superconducting states that the spin fluctuations present in Ti$_{0.6}$V$_{0.4}$ alloy are itinerant in nature. There is some evidence of the existence of preformed Cooper-pairs in the temperature range well above the superconducting transition temperature. Our study indicates that the interesting correlations between spin-fluctuations and superconductivity may actually be quite widespread amongst the superconducting materials, and not necessarily be confined only to certain classes of exotic compounds.