Nodeless d-wave superconductivity driven by charge fluctuations in monolayer FeSe on SrTiO3
Abstract
Monolayer FeSe and Fe(Te,Se) grown on SrTiO3 exhibit some of the highest superconducting transition temperatures among iron-based superconductors, yet their pairing mechanism and symmetry remain elusive. Motivated by the recent surprising discovery of nodeless d-wave superconductivity using scanning Josephson tunneling microscopy (SJTM) [T. Wei et al., arXiv:2610.38421 (2026)], we investigate superconductivity in monolayer FeSe/SrTiO$3$ (1L-FeSe/STO) within an extended Hubbard model incorporating both onsite and intersite Coulomb interactions among Fe 3d and Se 4p orbitals. We show that Fe-Se intersite Coulomb repulsion strongly enhances small-momentum p-d charge-transfer fluctuations, which mediate attractive intraorbital spin-singlet pairing interactions. These electronic fluctuations may be further enhanced by forward-scattering optical phonons of the SrTiO$3$ substrate. The resulting intrapocket attraction, together with residual repulsive interpocket interactions, stabilizes a mirror-odd, nodeless B1g (d-wave) superconducting state with opposite gap signs on the two electron pockets. Both Fe t2g and Se 4p orbitals contribute substantially to this multiorbital superconductivity. The calculated superconducting gap and density of states exhibit a two-peak structure, while the Josephson tunneling conductance displays a half-lattice-period modulation, in excellent agreement with experimental observations. Our results establish electronic charge-transfer fluctuations as a viable pairing mechanism for unconventional nodeless d-wave superconductivity in monolayer FeSe/STO.
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BibTeX
@misc{dong2026nodeless,
title = {{Nodeless $d$-wave superconductivity driven by charge fluctuations in monolayer FeSe on SrTiO$_3$}},
author = {Jin-Wei Dong and Sen Zhou and Jian Wang and Gang Su and Ziqiang Wang},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.00534},
eprint = {2611.00534},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.00534},
}
RIS
TY - UNPB
TI - Nodeless d-wave superconductivity driven by charge fluctuations in monolayer FeSe on SrTiO_3
AU - Jin-Wei Dong
AU - Sen Zhou
AU - Jian Wang
AU - Gang Su
AU - Ziqiang Wang
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.00534
UR - https://arxiv.org/abs/2611.00534
AB - Monolayer FeSe and Fe(Te,Se) grown on SrTiO_3 exhibit some of the highest superconducting transition temperatures among iron-based superconductors, yet their pairing mechanism and symmetry remain elusive. Motivated by the recent surprising discovery of nodeless d-wave superconductivity using scanning Josephson tunneling microscopy (SJTM) [T. Wei et al., arXiv:2610.38421 (2026)], we investigate superconductivity in monolayer FeSe/SrTiO$3$ (1L-FeSe/STO) within an extended Hubbard model incorporating both onsite and intersite Coulomb interactions among Fe 3d and Se 4p orbitals. We show that Fe-Se intersite Coulomb repulsion strongly enhances small-momentum p-d charge-transfer fluctuations, which mediate attractive intraorbital spin-singlet pairing interactions. These electronic fluctuations may be further enhanced by forward-scattering optical phonons of the SrTiO$3$ substrate. The resulting intrapocket attraction, together with residual repulsive interpocket interactions, stabilizes a mirror-odd, nodeless B_1g (d-wave) superconducting state with opposite gap signs on the two electron pockets. Both Fe t_2g and Se 4p orbitals contribute substantially to this multiorbital superconductivity. The calculated superconducting gap and density of states exhibit a two-peak structure, while the Josephson tunneling conductance displays a half-lattice-period modulation, in excellent agreement with experimental observations. Our results establish electronic charge-transfer fluctuations as a viable pairing mechanism for unconventional nodeless d-wave superconductivity in monolayer FeSe/STO.
ER -