Bogoliubov Fermi surfaces from pairing of emergent $j=3/2$ 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 = 3/2 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 on-site repulsion. Our calculations show that a time-reversal symmetry-breaking superconducting phase is favored, which displays Bogoliubov Fermi surfaces.