Field-temperature phase diagram of superconductivity in Sr 2RuO4-Ru under out-of-plane uniaxial pressure

Abstract

One of the interesting issues on the spin-triplet superconductor Sr2RuO4 (Tc 1.5 K) is the origin of the Tc enhancement up to about 3 K in the eutectic system Sr2RuO4-Ru. We have recently revealed a striking fact that Tc of pure Sr2RuO4 is also enhanced up to 3.2 K by uniaxial pressure along the c axis (P||c). When P||c is applied to Sr2RuO4-Ru, there is a crossover at P *||c ∼ 0.4 GPa from behavior attributable to interfacial superconductivity (SC) to behavior similar to that in pure Sr2RuO4 under P||c. We focus on the field-temperature phase diagrams of Sr2RuO4-Ru above and below P*||c. We revealed that the H-T curves of Sr2RuO4-Ru both above and below P*||c are concave-up. This fact suggests that the P||c-originated SC above P*||c as well as the interfacial SC below P*||c are granular-like. We also found that the H-T curves of these SCs do not scale with Tc's, which is possibly related to a difference in the spatial distribution of superconducting regions. © Published under licence by IOP Publishing Ltd.