(SNBr0.4)x: A superconductor of increased dimensionality

We have measured some of the superconducting properties of (SNBr0.4)x. The critical temperature is found to be enhanced over that of (SN)x by approximately 20%. The transition region is greatly narrowed. The perpendicular upper critical field is linear with temperature over a wide domain, attaining a value of about 400 Oe at absolute zero, and totally lacking the upward curvature shown by (SN)x. The parallel field is not greatly changed. On the basis of these and other measurements, it is shown that (SNBr0.4)x is a "three- dimensional" superconductor due to improved coupling between the (SN)x fibers. The parallel field appears to be paramagnetically limited. We believe that spin-orbit scattering is significant, despite the small atomic numbers involved, because of severe disorder and boundary effects. © 1979 The American Physical Society.