Magnetization studies on superconducting MgB2 – lower and upper critical fields and critical current density

Magnetization studies have been carried out on superconducting MgB2 (Tc=37 K) in the temperature range of 2–50 K and in magnetic fields up to 5 Tesla. From these measurements, values of the lower critical field Hc1(0), upper critical field Hc2(0) at 0 K are estimated to be ∼300 Oe and ∼12.5 Tesla, respectively, which yield a value of ∼26 for the Ginzburg–Landau parameter, κ. Magnetization hysteresis loops have been obtained at various temperatures from which the magnetization critical current density is estimated using Beanʹs critical state model.