Abstract
Enhanced superconductivity in the eutectic system is referred to as the 3-K phase of the spin-triplet superconductor because of its enhanced superconducting transition temperature of We have investigated the field-temperature phase diagram of the 3-K phase for fields parallel and perpendicular to the ab plane of using out-of-plane resistivity measurements. We have found an upturn curvature in the curve for and a rather gradual temperature dependence of close to for both and We have also investigated the dependence of on the angle between the field and the ab plane at several temperatures. Fitting the Ginzburg-Landau effective-mass model apparently fails to reproduce the angle dependence, particularly near and at low temperatures. We propose that all of these characteristic features can be explained, at least in a qualitative fashion, on the basis of a theory by Sigrist and Monien that assumes surface superconductivity with a two-component order parameter occurring at the interface between and Ru inclusions. This provides evidence of the chiral state postulated for the 1.5-K phase by several experiments.
- Received 31 July 2002
DOI:https://doi.org/10.1103/PhysRevB.67.214519
©2003 American Physical Society