title: Pairing of j=3/2 Fermions in Half-Heusler Superconductors.
abstract: We theoretically consider the superconductivity of the topological half-Heusler semimetals YPtBi and LuPtBi. We show that pairing occurs between j=3/2 fermion states, which leads to qualitative differences from the conventional theory of pairing between j=1/2 states. In particular, this permits Cooper pairs with quintet or septet total angular momentum, in addition to the usual singlet and triplet states. Purely on-site interactions can generate s-wave quintet time-reversal symmetry-breaking states with topologically nontrivial point or line nodes. These local s-wave quintet pairs reveal themselves as d-wave states in momentum space. Furthermore, due to the broken inversion symmetry in these materials, the s-wave singlet state can mix with a p-wave septet state, again with topologically stable line nodes. Our analysis lays the foundation for understanding the unconventional superconductivity of the half-Heuslers.
authors.affiliation: Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.|Department of Physics, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
authors.forename: P M R
authors.initials: PM
authors.lastname: Brydon
authors.affiliation: Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Limin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53201, USA.
authors.forename: M
authors.initials: M
authors.lastname: Weinert
authors.affiliation: Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53201, USA.
authors.forename: D F
authors.initials: DF
authors.lastname: Agterberg