Superconductivity from emerging magnetic moments

TL;DR

This paper demonstrates that multi-orbital Hubbard models can host a novel spin-triplet superconducting phase stabilized by emergent local moments in the spin-freezing crossover regime, influenced by spin anisotropy.

Contribution

It reveals a new mechanism for superconductivity driven by fluctuating magnetic moments away from quantum critical points in multi-orbital systems.

Findings

Superconducting dome appears below a non-Fermi liquid metallic phase.

Spin-triplet pairing is stabilized by local moments and spin anisotropy.

Potential realization in materials like strontium ruthenates and uranium compounds.

Abstract

Multi-orbital Hubbard models are shown to exhibit a spatially isotropic spin-triplet superconducting phase, where equal-spin electrons in different local orbitals are paired. This superconducting state is stabilized in the spin-freezing crossover regime, where local moments emerge in the metal phase, and the pairing is substantially assisted by spin anisotropy. The phase diagram features a superconducting dome below a non-Fermi liquid metallic region and next to a magnetically ordered phase. We suggest that this type of fluctuating-moment induced superconductivity, which is not originating from fluctuations near a quantum critical point, may be realized in spin-triplet superconductors such as strontium ruthenates and uranium compounds.