The thermodynamic critical field HC was deduced from the equilibrium magnetization of MgB2. The whole hysteresis loops were found to scale with HC; such that the M/HC, curves closely obeyed a universal behavior over a wide temperature range. The peaks in the pinning-force curves were found to scale with the vortex line energy as (HC)2. Moreover, the positions of the normalized Fp(max) occurred at about 0.1Hirr. This was significantly lower than that expected on the basis of the Dew-Hughes model.

On the Thermodynamic Critical Field in MgB2 Superconductor. K.A.Ziq: Journal of Alloys and Compounds, 2005, 397[1-2], 265-8