The Triplet Resonating Valence Bond State and Superconductivity in Hund's Metals

Abstract

A central idea in strongly correlated systems is that doping a Mott insulator leads to a superconductor by transforming the resonating valence bonds (RVBs) into spin-singlet Cooper pairs. Here, we argue that a spin-triplet RVB (tRVB) state, driven by spatially, or orbitally anisotropic ferromagnetic interactions can provide the parent state for triplet superconductivity. We apply this idea to the iron-based superconductors, arguing that strong onsite Hund's interactions develop intra-atomic tRVBs between the t${}_{2g}$ orbitals. On doping, the presence of two iron atoms per unit cell allows these inter-orbital triplets to coherently delocalize onto the Fermi surface, forming a fully gapped triplet superconductor. This mechanism gives rise to a unique staggered structure of onsite pair correlations, detectable as an alternating $\pi$ phase shift in a scanning tunnelling Josephson microscope.

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• Unveiling the Hybridization Process in a Quantum Critical Ferromagnet by Ultrafast Optical Spectroscopy
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• On the Spatial Locality of Electronic Correlations in LiFeAs
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• Switching between Mott-Hubbard and Hund physics in moiré quantum simulators
• Frustrated Kondo impurity triangle: A simple model of deconfinement
• Topological superconductivity from doping a triplet quantum spin liquid in a flat band system
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• Finite-momentum and field-induced pairings in orbital-singlet spin-triplet superconductors
• Triplet pairing, orbital selectivity and correlations in Iron-based superconductors
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• Non-collinear ferromagnetism in the Kondo lattice Ce${}_5$CoGe${}_2$