Progress in depositing MgB2 films on stainless steel substrate

We have made a progress in fabricating MgB2 films, ∼25 μm, on the stainless steel substrate by hybrid physical-chemical vapor deposition. The superconducting transition temperature is, TC (onset) = 39.6 K with a transition width, ΔT = 0.5 K. The characterization by scanning electron microscope and X-ray diffraction indicates that its structure is polycrystalline. At T = 0 K, the upper critical field HC2 is determined as 15.2 T by extrapolation from a polynomial fitting to the transition temperatures under various applied fields, TC(H). In the self field, the critical current density JC is determined as 3.74 MA/cm2 at T = 15 K by a magnetic measurement according to the Bean model.