Correspondence between macroscopic magnetic properties of fine-grained polycrystalline YBaCuO near Tc and those of ideal type II superconductors

Magnetic field dependence of equilibrium magnetization M(H) was calculated for type II superconductors (k = 100) of a size comparable to the London penetration depth. The interactions between the Abrikosov vortices and the surface were taken into account as well as the real grain size distribution in fine-grained polycrystalline HTSC. A good quantitative agreement between the calculated dependencies and the experimental quasi reversible magnetization curves (T = 85 K) was obtained