Revisiting electromagnetic response of superconductors in mean-field approximation

Abstract

In the standard mean-field treatment of superconductors, the electron-electron interactions are assumed to be written in terms of local density operators. However, more general interactions, such as pair-hopping interactions, may exist or may be generated in a low-energy effective Hamiltonian. In this work, we study the effect of correlated hopping interactions toward the electromagnetic response of superconductors. When only the Hamiltonian after the mean-field approximation is provided, one cannot unambiguously determine its electromagnetic response whenever such interactions are allowed. This work demonstrates that such interactions induce additional terms in the current operator, leading to modifications in the Meissner weight and optical conductivities that deviate from conventional expectations. These results underscore the need for caution when incorporating gauge fields into the BdG Hamiltonian.

6+7 pages, 3 figures; v2: discussions clarified, a new figure added

References in corpus (5)

• Band geometry, Berry curvature and superfluid weight
• Theory of optical responses in clean multi-band superconductors
• Nonreciprocal optical response in parity-breaking superconductors
• Current-enabled optical conductivity of superconductors
• Thermodynamic and electromagnetic properties of the eta-pairing superconductivity in the Penson-Kolb model

Cited by in corpus (4)

• Vertex correction for the linear and nonlinear optical responses in superconductors: multiband effect and topological superconductivity
• Circular-polarization-selective perfect reflection from chiral superconductors
• Third-harmonic generation in superconductors: Role of quantum geometry in the competition between Higgs mode and quasiparticles
• Intrinsic Nernst Effect from Berry Curvature in Superconductors