Large Enhancement of 3-K Phase Superconductivity in the Sr2RuO4-Ru Eutectic System by Uniaxial Pressure

TL;DR

Applying uniaxial pressure significantly enhances the superconducting volume fraction of the 3-K phase in Sr2RuO4-Ru eutectic system, indicating deep penetration of interfacial superconductivity and shedding light on the Tc enhancement mechanism.

Contribution

This study demonstrates that uniaxial pressure greatly increases the superconducting volume fraction in the 3-K phase, revealing the importance of interfacial effects in Tc enhancement.

Findings

Uniaxial pressure boosts the superconducting volume fraction from less than 0.5% to over 40%.

In-plane pressure enhances superconductivity more effectively than out-of-plane pressure.

Interfacial superconductivity penetrates deeply into Sr2RuO4 under uniaxial pressure.

Abstract

While the superconducting transition temperature Tc of Sr2RuO4 is 1.5 K, its onset Tc is enhanced as high as 3 K in the Sr2RuO4-Ru eutectic system, which is often referred to as the 3-K phase. We have investigated effects of uniaxial pressure on the non-bulk superconductivity in the 3-K phase. While Tc of pure Sr2RuO4 is known to be suppressed by hydrostatic pressure, a large enhancement of the superconducting volume fraction of the 3-K phase was observed for both out-of-plane and in-plane uniaxial pressures. Especially, under the in-plane pressure, the shielding fraction at 1.8 K of only less than 0.5% at 0 GPa exceeds 40% at 0.4 GPa. Such a large shielding fraction suggests that under the uniaxial pressure interfacial 3-K phase superconductivity penetrates deep into the bulk of Sr2RuO4. The present finding provides a significant implication to the unresolved origin of the enhancement of Tc to 3 K in the Sr2RuO4-Ru eutectic system.