Superconducting Critical Fields and Currents of Nb–Ti–N Thin Films in Continuous Magnetic Fields to 175 kG

Abstract

Superconducting critical current‐field measurements were made on a series of Nb–Ti–N thin film alloys (1000–8000 Å) prepared by reactive sputtering. Samples were measured in dc transverse and parallel fields. A pronounced maximum in the critical field occurs at approximately 20 mole % TiN. The extrapolated zero current value of H_c2 for this composition at 4.2°K was greater than 180 kG. Critical current densities in parallel fields are comparable to those of other high‐field bulk superconductors (10⁴ A/cm² at 150 kG). Films 2000 Å thick and 0.1 in. wide carried a few tenths of an ampere in fields as high as 120 kG in the transverse fields and as high as 140 kG in parallel fields. In the transverse orientation the critical current density appears to be independent of thickness. Possible application of these materials to miniature thin‐film solenoids is discussed.