Bogoliubov Fermi surfaces from pairing of emergent j= 32 fermions on the pyrochlore lattice

Abstract

We examine the appearance of superconductivity in the strong-coupling limit of the Hubbard model on the pyrochlore lattice. We focus upon the limit of half-filling, where the normal-state band structure realizes a j=32 semimetal. Introducing doping, we show that the pairing is favored in a J=2 quintet Eg state. The attractive interaction in this channel relies on the fact that Eg pairing on the pyrochlore lattice avoids the detrimental onsite repulsion. Our calculations show that a time-reversal symmetry-breaking superconducting phase is favored, which displays Bogoliubov Fermi surfaces.