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.

Close

PrevNext

View figure in article

• Multiband superconductivity
• Quasiparticles & collective excitations
• Spin-orbit coupling
• Superconducting fluctuations
• Superconductivity
• Superconductors
• Unconventional superconductors