Vortex coalescence and type-1.5 superconductivity in Sr2RuO4

TL;DR

This paper proposes that Sr2RuO4 exhibits type-1.5 superconductivity due to multiband and multiorbital effects, leading to vortex coalescence and nonmonotonic intervortex forces.

Contribution

It introduces the concept of type-1.5 superconductivity in Sr2RuO4, explaining vortex behavior through multiband and multiorbital interactions.

Findings

Vortex coalescence observed in Sr2RuO4.

Sr2RuO4 is characterized as a type-1.5 superconductor.

Intervortex forces are nonmonotonic due to multiple coherence lengths.

Abstract

Recently vortex coalescence was reported in superconducting Sr2RuO4 by several experimental groups for fields applied along the c-axis. We argue that Sr2RuO4 is a type-1.5 superconductor with long-range attractive, short-range repulsive intervortex interaction. The type-1.5 behavior stems from an interplay of the two orbital degrees of freedom describing this chiral superconductor together with the multiband nature of the superconductivity. These multiple degrees of freedom give rise to multiple coherence lengths, some of which are larger and some smaller than the magnetic field penetration length, resulting in nonmonotonic intervortex forces.