Optical response of the Leggett mode in multiband superconductors in the linear response regime

Abstract

We study optical responses of Leggett modes in multiband superconductors in the linear response regime. The Leggett mode is a collective mode unique to multiband superconductors that arises from relative phase fluctuations of superconducting orders for different bands. We use the Ginzburg-Landau (GL) description to study the collective modes in multiband systems. We find that multiband superconductors generally allow a linear coupling between the Leggett mode and external electric fields due to the presence of a cross term between different components of superconducting orders in the GL theory. The presence of a linear coupling for the Leggett mode is in sharp contrast with the absence of that for Higgs (amplitude) modes in single-band superconductors that only support nonlinear optical responses such as third harmonic generation (THG). We further confirm such a linear coupling in multiband superconductors by a more microscopic description based on a diagrammatic approach. We study the collective modes within the random phase approximation (RPA) and compute their contribution to the linear optical conductivity. These findings suggest a new route to observe the Leggett mode by optical absorption.

13 pages, 4 figures

References in corpus (12)

• Amplitude / Higgs Modes in Condensed Matter Physics
• Field-induced superconducting phase of FeSe in the BCS-BEC cross-over
• Observation of Leggett's collective mode in a multi-band MgB2 superconductor
• Nonlinear electromagnetic response and Higgs mode excitation in BCS superconductors with impurities
• Nonlinear optical response of collective modes in multiband superconductors assisted by nonmagnetic impurities
• Signature of the Leggett mode in the A1g Raman response: from MgB2 to iron-based superconductors
• Theory of Raman response in a superconductor with extended s-wave symmetry: Application to Fe-pnictides
• Collective modes in multiband superfluids and superconductors: Multiple dynamical classes
• Quasiclassical Theory on Third-Harmonic Generation in Conventional Superconductors with Paramagnetic Impurities
• Coherent current states in a two-band superconductor
• Collective modes in multiband superconductors: Raman scattering in iron selenides
• Leggett mode in a strong-coupling model of iron arsenide superconductors

Cited by in corpus (13)

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• Quench-drive spectroscopy and high-harmonic generation in BCS superconductors
• Classification of Lifshitz invariant in multiband superconductors: an application to Leggett modes in the linear response regime in Kagome lattice models
• Linear spectroscopy of collective modes and the gap structure in two-dimensional superconductors
• Optically active Higgs and Leggett modes in multiband pair-density-wave superconductors with Lifshitz invariant
• Vertex correction for the linear and nonlinear optical responses in superconductors: multiband effect and topological superconductivity
• Reducing the frequency of the Higgs mode in a helical superconductor coupled to an LC-circuit
• Amplitude, phase, and topological fluctuations shaping the complex phase diagram of two-dimensional superconductors
• Two-dimensional coherent spectroscopy of disordered superconductors in the narrow-band and broad-band limits
• Phenomenological Ginzburg-Landau theory for triple-Q magnetic orders on a hexagonal lattice
• Landau levels and optical conductivity in the mixed state of a generic Weyl superconductor
• Raman response of collective modes in multicomponent superconductors