A less controversial method was used to analyze the imaginary part of the alternating-current susceptibility of MgB2. The pinning potential barrier Uo(T,H) was obtained near the melting curve. It was found that Uo(T,H) depended linearly upon both the temperature and the applied field.

Pinning Characteristics of MgB2 Near the Melting Curve. J.K.F.Yau, M.J.Qin, H.K.Liu, S.X.Dou, C.M.Lee, Y.S.Han, L.J.Shen, X.Jin: Superconductor Science and Technology, 2002, 15, 619-23