Multicomponent order parameter superconductivity of Sr2RuO4 revealed by topological junctions

M. S. Anwar; R. Ishiguro; T. Nakamura; M. Yakabe; S. Yonezawa; H. Takayanagi; Y. Maeno

doi:10.1103/PhysRevB.95.224509

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Multicomponent order parameter superconductivity of Sr2RuO4 revealed by topological junctions

M. S. Anwar, R. Ishiguro, T. Nakamura, M. Yakabe, S. Yonezawa, H. Takayanagi, Y. Maeno

DOI 10.1103/PhysRevB.95.224509 · Physical Review B

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Abstract

Single crystals of the Sr2RuO4-Ru eutectic system are known to exhibit enhanced superconductivity at 3 K in addition to the bulk superconductivity of Sr2RuO4 at 1.5 K. The 1.5 K phase is believed to be a spin-triplet, chiral p-wave state with a multicomponent order parameter, giving rise to chiral domain structure. In contrast, the 3 K phase is attributable to enhanced superconductivity of Sr2RuO4 in the strained interface region between Ru inclusion of a few to tens of micrometers in size and the surrounding Sr2RuO4. We investigate the dynamic behavior of a topological junction, where a superconductor is surrounded by another superconductor. Specifically, we fabricated Nb/Ru/Sr2RuO4 topological superconducting junctions, in which the difference in phase winding between the s-wave superconductivity in Ru microislands induced from Nb and the superconductivity of Sr2RuO4 mainly governs the junction behavior. Comparative results of the asymmetry, hysteresis, and noise in junctions with different sizes, shapes, and configurations of Ru inclusions are explained by the chiral domain-wall motion in these topological junctions. Furthermore, a striking difference between the 1.5 and 3 K phases is clearly revealed: the large noise in the 1.5 K phase sharply disappears in the 3 K phase. These results confirm the multicomponent order-parameter superconductivity of the bulk Sr2RuO4, consistent with the chiral p-wave state, and the proposed nonchiral single-component superconductivity of the 3 K phase.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Sr2RuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.5	Pressure not reported	unknown
Sr2RuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3	Pressure not reported	onset
Nb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	9	Pressure not reported	onset