Specific heat anomalies in the magnetic borocarbide superconductors Y1−xRxNi2B2C (R=Gd, Dy, Ho, and Er)

Abstract

The specific heat anomalies associated with the superconducting transition of Y1−xRxNi2B2C (R=Gd, Dy, Ho, and Er) show a common correlation between the specific heat jump ΔC and the transition temperature Tc with an almost quadratic relation ΔC∝Tc2 in all these solid solutions. The antiferromagnetic superconductor DyNi2B2C with TN>Tc as well as Ho and ErNi2B2C, which are paramagnetic at Tc, fit into the same scheme of ΔC versus Tc as the pseudoquaternaries. A simple description which combines the weak-coupling results of magnetic pair breaking theory with strong-coupling corrections explains reasonably well the quadratic relation between ΔC and Tc. The overall agreement between this model and our experimental results indicates that the Sommerfeld value γ and hence the electronic density of states are almost constant within these heavy rare-earth solid solutions and their boundary compounds.

Source-reported materials — not catalogue approval

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