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

Zhihai Liu; Luyang Wang

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arXiv · 2505.13606

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

Zhihai Liu·Luyang Wang

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Abstract

Previous investigations have revealed that the Weyl superconductor (WeylSC), realized in a superconductor-topological insulator heterostructure, can exhibit the Landau levels (LLs) of Bogoliubov quasiparticles in the presence of a vortex lattice. Here, we investigate the low-energy quasiparticle (QP) excitations in the mixed state of heterostructure WeylSCs with unconventional pairing. We find that the spin-singlet $d$-wave pairing induces flat Dirac-LLs of Bogoliubov QPs, whereas the excitation spectra for the spin-triplet chiral $p$-wave pairing show noticeable dispersion, except for the chiral symmetry-protected, dispersionless, zeroth Landau level (ZLL). Distinct QP excitations in the vortex lattice of WeylSCs result in different optical responses, which are manifested as characteristic magneto-optical conductivity curves. We also show 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 mixed state of a heterostructure topological superconductor.

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Zhihai Liu, Luyang Wang. 2025-05-19. Quasiparticles and optical conductivity in the mixed state of Weyl superconductors with unconventional pairing. https://arxiv.org/abs/2505.13606

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