Study of magnetic field effect on the specific heat and entropy in DyBa2Cu3O7−x

The change in the specific heat by the application of magnetic field up to 16 T for high temperature superconductor system for DyBa2Cu3O7−x by Revaz et al. [23] is examined through the phenomenological Ginzburg–Landau(G–L) theory of anisotropic Type-II superconductors. The observed specific heat anomaly near Tc with magnetic field is explained qualitatively through the expression 〈ΔC〉=(Ba/Tc) t/(1−t)(αΘ(γ)/λ2m(0)), which is the anisotropic formulation of the G–L theory in the London limit developed by Kogan and coworkers; relating to the change in specific heat ΔC for the variation of applied magnetic field for different orientations with c-axis. The analysis of this equation explains satisfactorily the specific heat anomaly near Tc and determines the anisotropic ratio γ as 5.608, which is close to the experimental value 5.3±0.5 given in the paper of Revaz et al. for this system.