Critical Current Densities in Superconducting Niobium Films Sputtered Reactively in the Presence of Nitrogen Gas

A critical current density of about 2 × 105 A/cm2 in a transverse external field of 73 kOe, parallel to the film plane, was obtained at liquid-helium temperature for niobium films deposited on glass substrates by sputtering technique in an argon atmosphere with a dilute addition of nitrogen. This critical current density is larger than any other reported values for refractory metal carbides and nitrides with the NaCl structure.