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Subgap two-particle spectral weight in disordered s -wave superconductors: Insights from mode coupling approach

Poduval, PP and Samanta, A and Gupta, P and Trivedi, N and Sensarma, R (2022) Subgap two-particle spectral weight in disordered s -wave superconductors: Insights from mode coupling approach. In: Physical Review B, 106 (6).

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Official URL: https://doi.org/10.1103/PhysRevB.106.064512


We study the two-particle spectral functions and collective modes of weakly disordered superconductors using a disordered attractive Hubbard model on a square lattice. We show that the disorder-induced scattering between collective modes leads to a finite subgap spectral weight in the long-wavelength limit. In general, the spectral weight is distributed between the phase and the Higgs channels, but as we move towards half filling the Higgs contribution dominates. The inclusion of the density fluctuations lowers the frequency at which this mode occurs and results in the phase channel gaining a larger contribution to this subgap mode. Near half filling, the proximity of the system to the charge density wave instability leads to strong fluctuations of the effective disorder at the commensurate wave vector ([π,π]). We develop an analytical mode coupling approach where the pure Goldstone mode in the long-wavelength limit couples to the collective mode at [π,π]. This provides insight into the location and distribution of the two-particle spectral weights between the Higgs and the phase channels.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to the American Physical Society.
Keywords: Charge density waves; Hubbard model; Shear waves; Superconducting materials, Collective modes; Disordered superconductors; Half-filling; Long-wavelength limits; Mode coupling; S-waves; Spectral function; Spectral weight; Two particles; Wave superconductors, Charge density
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 06 Oct 2022 10:46
Last Modified: 06 Oct 2022 10:46
URI: https://eprints.iisc.ac.in/id/eprint/77233

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