Interesting Diameter-Dependent Upper Critical Field in Nb 2 Pd 0.77 S 5 Superconductor

The extremely large upper critical field in PdS 2 -related superconductors has been a puzzling problem in recent years. In this work, we grow a series of high-quality Nb 2 Pd 0.77 S 5 filamentary samples with different diameters and investigate the influence of size of the sample on the upper critical field. It is interesting to find that the upper critical field is significantly enhanced with the decreasing of the diameter of the filamentary sample. The extremely large upper critical field in Nb 2 Pd 0.77 S 5 compounds can be attributed to the thin superconducting shapes.