Anisotropic superconductivity of Sr2RuO4

We report the upper critical field H c2 of single crystalline Sr 2 RuO 4 , which is the only known layered-perovskite superconductor without copper. The ratio H c2∥ ab / H c2∥ c = 26 indicates that the ruthenate is a highly anisotropic superconductor. In addition, we found a peculiar second dissipation peak only when the flux lines, as well as their induced motions, are within the ab -planes.