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Main Authors: Nagashima, Raigo, Mouilleron, Titouan, Tsuji, Naoto
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2410.18438
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author Nagashima, Raigo
Mouilleron, Titouan
Tsuji, Naoto
author_facet Nagashima, Raigo
Mouilleron, Titouan
Tsuji, Naoto
contents Lifshitz invariant is a symmetry invariant composed of multiple order parameters that contain a single spatial derivative in a Ginzburg-Landau (GL) free energy, which may induce a nonuniform configuration of the order parameters. In multiband superconductors, we find phase transitions from a uniform superconducting state to qualitatively distinct two pair-density-wave (PDW) states with small and large momenta $\boldsymbol{q}$ based on the GL theory. The former is induced by the Lifshitz invariant, while the latter originates from the drag effect. In the PDW states, the Higgs and Leggett modes (i.e., collective amplitude and relative phase oscillations of the order parameters) are shown to couple to electromagnetic fields linearly. We construct microscopic models of multiband superconductors with Lifshitz invariant that exhibit PDW states, and calculate the linear optical conductivity using the diagrammatic approach. We find optically active Higgs and Leggett modes in the small $\boldsymbol{q}$ PDW state, indicating that the PDW state is a suitable platform to explore collective modes of multiband superconductors in the linear response regime.
format Preprint
id arxiv_https___arxiv_org_abs_2410_18438
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Optically active Higgs and Leggett modes in multiband pair-density-wave superconductors with Lifshitz invariant
Nagashima, Raigo
Mouilleron, Titouan
Tsuji, Naoto
Superconductivity
Lifshitz invariant is a symmetry invariant composed of multiple order parameters that contain a single spatial derivative in a Ginzburg-Landau (GL) free energy, which may induce a nonuniform configuration of the order parameters. In multiband superconductors, we find phase transitions from a uniform superconducting state to qualitatively distinct two pair-density-wave (PDW) states with small and large momenta $\boldsymbol{q}$ based on the GL theory. The former is induced by the Lifshitz invariant, while the latter originates from the drag effect. In the PDW states, the Higgs and Leggett modes (i.e., collective amplitude and relative phase oscillations of the order parameters) are shown to couple to electromagnetic fields linearly. We construct microscopic models of multiband superconductors with Lifshitz invariant that exhibit PDW states, and calculate the linear optical conductivity using the diagrammatic approach. We find optically active Higgs and Leggett modes in the small $\boldsymbol{q}$ PDW state, indicating that the PDW state is a suitable platform to explore collective modes of multiband superconductors in the linear response regime.
title Optically active Higgs and Leggett modes in multiband pair-density-wave superconductors with Lifshitz invariant
topic Superconductivity
url https://arxiv.org/abs/2410.18438