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| Main Authors: | , |
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| Format: | Preprint |
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2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2605.05433 |
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| _version_ | 1866913097037381632 |
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| author | Islam, Kazi Ranjibul Chubukov, Andrey |
| author_facet | Islam, Kazi Ranjibul Chubukov, Andrey |
| contents | We analyze the spectrum of collective modes in a superconductor in which pairing is mediated by long-range nematic fluctuations. Previous experimental and theoretical studies have found that the superconducting gap in such a system is highly anisotropic and, at any finite $T<T_c$, vanishes on four arcs of the Fermi surface, even when the pairing symmetry is $s$ wave ($s^{+-}$ between hole and electron pockets). We derive the expression for the pair susceptibility $χ(\mathbf{q},Ω)$ at finite momentum $\mathbf{q}$ and frequency $Ω$ deep in the superconducting phase. We analyze the spectral function, $\operatorname{Im}χ(\mathbf{q},Ω)$, and its pole structure in the transverse (phase) and longitudinal (amplitude) channels, and compare the results with those of a conventional $s$-wave superconductor. We find that the analytic structure of the pair susceptibility in both channels is qualitatively distinct from that in a BCS superconductor. This gives rise to a highly unconventional dispersion of phase and amplitude collective modes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_05433 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Superconductivity mediated by nematic fluctuations -- the dispersion of collective modes Islam, Kazi Ranjibul Chubukov, Andrey Superconductivity We analyze the spectrum of collective modes in a superconductor in which pairing is mediated by long-range nematic fluctuations. Previous experimental and theoretical studies have found that the superconducting gap in such a system is highly anisotropic and, at any finite $T<T_c$, vanishes on four arcs of the Fermi surface, even when the pairing symmetry is $s$ wave ($s^{+-}$ between hole and electron pockets). We derive the expression for the pair susceptibility $χ(\mathbf{q},Ω)$ at finite momentum $\mathbf{q}$ and frequency $Ω$ deep in the superconducting phase. We analyze the spectral function, $\operatorname{Im}χ(\mathbf{q},Ω)$, and its pole structure in the transverse (phase) and longitudinal (amplitude) channels, and compare the results with those of a conventional $s$-wave superconductor. We find that the analytic structure of the pair susceptibility in both channels is qualitatively distinct from that in a BCS superconductor. This gives rise to a highly unconventional dispersion of phase and amplitude collective modes. |
| title | Superconductivity mediated by nematic fluctuations -- the dispersion of collective modes |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2605.05433 |