The change in thermodynamic quantities (e.g., entropy, specific heat etc.) by the application of magnetic field in the case of the high-Tc superconductor YBCO system is examined phenomenological by the Ginzburg–Landau theory of anisotropic type-II superconductors. An expression for the change in the entropy (ΔS) and change in specific heat (ΔC) in a magnetic field for any general orientation of an applied magnetic field Ba with respect to the crystallographic c-axis is obtained. The observed large reduction of specific heat anomaly just below the superconducting transition and the observed variation of entropy with magnetic field are explained quantitatively.
Low-temperature specific heat of an extreme type-II superconductor at high magnetic fields