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 spinsinglet 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, giving rise to a fully gapped triplet superconductor with a staggered structure of onsite pair correlations, detectable as an alternating π phase shift in a scanning Josephson tunnelling microscope.

Frustrated Kondo impurity triangle: A simple model of deconfinement

“…The study of doped spin-liquids at the vicinity of a Mott-delocalization has captivated the community for a long time and is believed to be of fundamental importance in cuprate [5] and iron-based [6] high-T c superconductors. The experiments on organic salts, e.g.…”

Superconductivity and phonon self-energy effects in Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$

“…Introduction -Since the discovery of the multi-band iron-based superconductors (FeSCs) in 2008 [1], a unified understanding the pairing mechanism in FeSCs remains in a focus of attention [2][3][4][5][6][7][8]. One step towards understanding the pairing mechanism is to study the superconducting (SC) gaps on different pockets of the Fermi surface (FS) [5,9].…”