Gapless superconductivity from extremely dilute magnetic disorder in 2H-NbSe2-xSx

Fuente: arXiv
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Autori principali: Moreno, Jose Antonio, Roig, Mercè, Barrena, Víctor, Herrera, Edwin, Ruiz, Alberto M., Mañas-Valero, Samuel, Fente, Antón, Smeets, Anita, Aragón, Jazmín, Fasano, Yanina, Wu, Beilun, Gastiasoro, Maria N., Coronado, Eugenio, Baldoví, José J., Andersen, Brian M., Guillamón, Isabel, Suderow, Hermann
Natura: Preprint
Pubblicazione: 2025
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author Moreno, Jose Antonio
Roig, Mercè
Barrena, Víctor
Herrera, Edwin
Ruiz, Alberto M.
Mañas-Valero, Samuel
Fente, Antón
Smeets, Anita
Aragón, Jazmín
Fasano, Yanina
Wu, Beilun
Gastiasoro, Maria N.
Coronado, Eugenio
Baldoví, José J.
Andersen, Brian M.
Guillamón, Isabel
Suderow, Hermann
author_facet Moreno, Jose Antonio
Roig, Mercè
Barrena, Víctor
Herrera, Edwin
Ruiz, Alberto M.
Mañas-Valero, Samuel
Fente, Antón
Smeets, Anita
Aragón, Jazmín
Fasano, Yanina
Wu, Beilun
Gastiasoro, Maria N.
Coronado, Eugenio
Baldoví, José J.
Andersen, Brian M.
Guillamón, Isabel
Suderow, Hermann
contents Most superconducting materials exhibit a vanishing density of states at the Fermi level and Anderson's theorem posits that the superconducting gap is robust against nonmagnetic disorder. Although dilute magnetic impurities lead to localized in-gap states, these states typically have no bearing on the material's bulk superconducting properties. However, numerous experiments reveal a finite density of states at the Fermi level in systems with an apparently negligible number of magnetic impurities. Here, using scanning tunneling microscopy and self-consistent Bogoliubov-de Gennes calculations, we find that gapless superconductivity emerges in 2H-NbSe2-xSx at remarkably low magnetic impurity concentrations. Furthermore, our density functional theory calculations and in-gap quasiparticle interference measurements demonstrate that the Se-S substitution significantly modifies the band structure. This modification favours nesting and dictates the in-gap scattering for x>0, in stark contrast to the dominant charge density wave interactions in pure 2H-NbSe2. Our findings reveal an unusual superconducting response to disorder and highlight the importance of incorporating material-specific band structures in the understanding of a superconductor's response to even very low concentrations of magnetic impurities.
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id arxiv_https___arxiv_org_abs_2508_00435
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Gapless superconductivity from extremely dilute magnetic disorder in 2H-NbSe2-xSx
Moreno, Jose Antonio
Roig, Mercè
Barrena, Víctor
Herrera, Edwin
Ruiz, Alberto M.
Mañas-Valero, Samuel
Fente, Antón
Smeets, Anita
Aragón, Jazmín
Fasano, Yanina
Wu, Beilun
Gastiasoro, Maria N.
Coronado, Eugenio
Baldoví, José J.
Andersen, Brian M.
Guillamón, Isabel
Suderow, Hermann
Superconductivity
Mesoscale and Nanoscale Physics
Materials Science
Strongly Correlated Electrons
Most superconducting materials exhibit a vanishing density of states at the Fermi level and Anderson's theorem posits that the superconducting gap is robust against nonmagnetic disorder. Although dilute magnetic impurities lead to localized in-gap states, these states typically have no bearing on the material's bulk superconducting properties. However, numerous experiments reveal a finite density of states at the Fermi level in systems with an apparently negligible number of magnetic impurities. Here, using scanning tunneling microscopy and self-consistent Bogoliubov-de Gennes calculations, we find that gapless superconductivity emerges in 2H-NbSe2-xSx at remarkably low magnetic impurity concentrations. Furthermore, our density functional theory calculations and in-gap quasiparticle interference measurements demonstrate that the Se-S substitution significantly modifies the band structure. This modification favours nesting and dictates the in-gap scattering for x>0, in stark contrast to the dominant charge density wave interactions in pure 2H-NbSe2. Our findings reveal an unusual superconducting response to disorder and highlight the importance of incorporating material-specific band structures in the understanding of a superconductor's response to even very low concentrations of magnetic impurities.
title Gapless superconductivity from extremely dilute magnetic disorder in 2H-NbSe2-xSx
topic Superconductivity
Mesoscale and Nanoscale Physics
Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2508.00435