On the thermodynamic critical field in MgB2 superconductor

The thermodynamic critical field Hc has been obtained from the equilibrium magnetization of MgB2 superconductor. The entire hysteresis loops have been found to scale with Hc such that the M/Hc, curves follow closely universal behavior over a wide temperature range. The peaks in the pinning force curves have been found to scale with the vortex line energy as (Hc)2. Moreover, the positions of the normalized Fp(max) occur at about 0.1Hirr significantly lower than what is expected from Dew-Hughes model.