Entropy and spin susceptibility of s-wave type-II superconductors near Hc2

Abstract

A theoretical study is performed on the entropy Ss and the spin susceptibility χs near the upper critical field Hc2 for s-wave type-II superconductors with arbitrary impurity concentrations. The changes of these quantities through Hc2 may be expressed as [Ss(T,B)−Ss(T,0)]/[Sn(T)−Ss(T,0)]=1−αS(1−B/Hc2)≈(B/Hc2)αS, for example, where B is the average flux density and Sn denotes entropy in the normal state. It is found that the slopes αS and αχ at T=0 are identical, connected directly with the zero-energy density of states, and vary from 1.72 in the dirty limit to 0.5–0.6 in the clean limit. This mean-free-path dependence of αS and αχ at T=0 is quantitatively the same as that of the slope αρ(T=0) for the flux-flow resistivity studied previously. The result suggests that Ss(B) and χs(B) near T=0 are convex downward (upward) in the dirty (clean) limit, deviating substantially from the linear behavior ∝B/Hc2. The specific-heat jump at Hc2 also shows fairly large mean-free-path dependence.

Source-reported materials — not catalogue approval

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