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arXiv · 2306.16611

Bardasis-Schrieffer-like phase mode in a superconducting bilayer

Nico A. Hackner·P. M. R. Brydon
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Abstract

We theoretically study the low-lying collective modes of an even-parity spin-singlet superconducting bilayer, where strong spin-orbit coupling leads to a closely competing odd-parity pairing state. We develop a gauge-invariant theory for the coupling of phase fluctuations to an external electromagnetic field and show that the competing odd-parity pairing instability gives rise to a Bardasis-Schrieffer-like phase mode within the excitation gap. Accounting for the long-range Coulomb interaction, however, we find that this mode is converted into an antisymmetric plasmon and is likely pushed into the quasiparticle continuum.

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Nico A. Hackner, P. M. R. Brydon. 2023-06-29. Bardasis-Schrieffer-like phase mode in a superconducting bilayer. https://doi.org/10.1103/physrevb.108.l220505

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