Department of Physics • University of Cologne

In this talk, I show that when the time reversal symmetry is broken in a multi-component superconducting condensate without inversion symmetry the resulting Bogoliubov quasiparticles generically exhibit mini Bogoliubov-Fermi (BF) surfaces, for small superconducting order parameter. The absence of inversion symmetry makes the BF surfaces stable with respect to weak perturbations. With sufficient increase of the order parameter, however, the Bogoliubov Fermi surface may disappear through a Lifshitz transition, and the spectrum this way become fully gapped [1]. Furthermore, an explicit example for the emergence of BF surfaces in non-centrosymmetric multicomponent superconductors is given by the discussion of d-wave superconductivity in Rarita- Schwinger-Weyl semimetals [2]. The three-dimensional Rarita-Schwinger-Weyl semimetals host pseudospin-3/2 fermions at a fourfold linear band crossing point and the spin-3/2 nature of the fermions allows for the formation of spin-2 Cooper pairs. [1] Julia M. Link and Igor F. Herbut, Arxiv:2006.10899 [2] Julia M. Link and Igor F. Herbut, Phys. Rev. B 101, 184503 (2020)