Collective excitations of a BCS superfluid in the presence of two sublattices

  title={Collective excitations of a BCS superfluid in the presence of two sublattices},
  author={M. Iskin},
  journal={Physical Review A},
  • M. Iskin
  • Published 1 January 2020
  • Physics
  • Physical Review A
We consider a generic Hamiltonian that is suitable for describing a uniform BCS superfluid on a lattice with a two-point basis and study its collective excitations at zero temperature. For this purpose, we first derive a Gaussian effective action for the pairing fluctuations and then extract the low-energy dispersion relations for the in-phase Goldstone and out-of-phase Leggett modes along with the corresponding amplitude (i.e., the so-called Higgs) ones. We find that while the Goldstone mode… Expand
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