Fractionalized Superconductivity Mediated by Majorana Fermions in the Kitaev-Kondo Lattice

Abstract

Superconductivity usually emerges from a metallic normal state which follows the Fermi-liquid paradigm. If, in contrast, the normal state is a fractionalized non-Fermi liquid, then pairing may either eliminate fractionalization via a Higgs-type mechanism leading to a conventional superconducting state, or pairing can occur in the presence of fractionalization. Here we discuss a simple model for the latter case: Using a combination of perturbation theory and functional renormalization group, we show that the Kitaev--Kondo lattice model displays a fractionalized superconducting phase at weak Kondo coupling. This phase is characterized by Cooper pairing of conventional electronic quasiparticles, coexisting with a spin-liquid background and topological order. Depending on the sign of the Kitaev coupling, we find the pairing to be either of chiral $d$-wave or $p$-wave type for extended doping regions around the van-Hove filling. We discuss applications and extensions.

(7+7 pages, 3+7 figures)

References in corpus (16)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Weak magnetism and non-Fermi liquids near heavy-fermion critical points
• Fractionalized Fermi liquids
• Exact results for spin dynamics and fractionization in the Kitaev Model
• Spin-S Kitaev model: Classical Ground States, Order by Disorder and Exact Correlation Functions
• Orbital-selective Mott transitions: Heavy fermions and beyond
• Correlated Dirac Particles and Superconductivity on the Honeycomb Lattice
• Anomalous Quantum Oscillations in a Heterostructure of Graphene on a Proximate Quantum Spin Liquid
• Reference results for the momentum space functional renormalization group
• The underdoped cuprates as fractionalized Fermi liquids: transition to superconductivity
• Multiflavor Mott insulators in quantum materials and ultracold atoms
• divERGe implements various Exact Renormalization Group examples
• Symmetries and anomalies of Kitaev spin-$S$ models: Identifying symmetry-enforced exotic quantum matter
• Topological superconductivity induced by a Kitaev spin liquid
• Breakdown of order-fractionalization in the CPT model
• Chern number landscape of spin-orbit coupled chiral superconductors