Quasiparticles and optical conductivity in the mixed state of Weyl superconductors with unconventional pairing

Previous investigations have revealed that the Weyl superconductor (WeylSC) and the two-dimensional (2D) nodal superconductor, realized through a topological insulator-superconductor heterostructure, can exhibit a Dirac-like Landau level (LL) structure that scales with $\sqrt{n}$ in the presence of a vortex lattice, where $n$ is the index of the LLs. Here, we investigate the excitation spectrum in the mixed state of WeylSCs with unconventional pairing and find that, unlike in the spin-singlet case, QP bands for the spin-triplet pairing show surprising dispersion, except for the chiral symmetry-protected, dispersionless zeroth Landau level (ZLL). Different pairing symmetries in WeylSCs also result in distinct magneto-optical responses, manifested as characterized magneto-optical conductivity curves. We also reveal that, compared to the topologically protected, charge-neutral, localized Majorana zero mode (MZM), the chiral symmetry-protected ZLL is non-charge-neutral and delocalized. Both of these zero modes may be observed in the vortex of a superconductor heterostructure.