Singlet, triplet, and mixed all-to-all pairing states emerging from incoherent fermions

Fuente: arXiv
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Autori principali: Sutradhar, Jagannath, Ruhman, Jonathan, Klein, Avraham
Natura: Preprint
Pubblicazione: 2024
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author Sutradhar, Jagannath
Ruhman, Jonathan
Klein, Avraham
author_facet Sutradhar, Jagannath
Ruhman, Jonathan
Klein, Avraham
contents The electron-electron and electron-phonon coupling in complex materials can be more complicated than simple density-density interactions, involving intertwined dynamics of spin, charge, and spatial symmetries. This motivates studying universal models with complex interactions, and studying whether in this case BCS-type singlet pairing is still the ``natural'' fate of the system. To this end, we construct a Yukawa-SYK model with nonlocal couplings in both spin and charge channels. Furthermore, we provide for time-reversal-symmetry breaking dynamics by averaging over the Gaussian Unitary ensemble rather than the Orthogonal ensemble. We find that the ground state of the system can be an orbitally nonlocal superconducting state arising from incoherent fermions with no BCS-like analog. The superconductivity has an equal tendency to triplet and singlet pairing states separated by a non-Fermi liquid phase. We further study the fate of the system within the superconducting phase and find that the expected ground state, away from the critical point, is a mixed singlet/triplet state. Finally, we find that while at $T_c$ the triplet and singlet transitions are dual to one another, below $T_c$ the duality is broken, with the triplet state more susceptible to orbital fluctuations just by virtue of its symmetry. Our results indicate that such fluctuation-induced mixed states may be an inherent feature of strongly correlated materials.
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id arxiv_https___arxiv_org_abs_2404_03731
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Singlet, triplet, and mixed all-to-all pairing states emerging from incoherent fermions
Sutradhar, Jagannath
Ruhman, Jonathan
Klein, Avraham
Strongly Correlated Electrons
Superconductivity
The electron-electron and electron-phonon coupling in complex materials can be more complicated than simple density-density interactions, involving intertwined dynamics of spin, charge, and spatial symmetries. This motivates studying universal models with complex interactions, and studying whether in this case BCS-type singlet pairing is still the ``natural'' fate of the system. To this end, we construct a Yukawa-SYK model with nonlocal couplings in both spin and charge channels. Furthermore, we provide for time-reversal-symmetry breaking dynamics by averaging over the Gaussian Unitary ensemble rather than the Orthogonal ensemble. We find that the ground state of the system can be an orbitally nonlocal superconducting state arising from incoherent fermions with no BCS-like analog. The superconductivity has an equal tendency to triplet and singlet pairing states separated by a non-Fermi liquid phase. We further study the fate of the system within the superconducting phase and find that the expected ground state, away from the critical point, is a mixed singlet/triplet state. Finally, we find that while at $T_c$ the triplet and singlet transitions are dual to one another, below $T_c$ the duality is broken, with the triplet state more susceptible to orbital fluctuations just by virtue of its symmetry. Our results indicate that such fluctuation-induced mixed states may be an inherent feature of strongly correlated materials.
title Singlet, triplet, and mixed all-to-all pairing states emerging from incoherent fermions
topic Strongly Correlated Electrons
Superconductivity
url https://arxiv.org/abs/2404.03731