# Novel attractive pairing interaction in strongly correlated superconductors

### Submission summary

 As Contributors: Tanmoy Das Arxiv Link: https://arxiv.org/abs/1906.01312v1 Date submitted: 2019-06-06 Submitted by: Das, Tanmoy Submitted to: SciPost Physics Domain(s): Theoretical Subject area: Condensed Matter Physics - Theory

### Abstract

Conventional and unconventional superconductivity, respectively, arise from attractive (electron-phonon) and repulsive (many-body Coulomb) interactions with fixed-sign and sign-reversal pairing symmetries. Although heavy-fermions, cuprates, and pnictides are widely believed to be unconventional superconductors, recent evidence in the former materials indicate the presence of a novel conventional pairing symmetry beyond the electron-phonon coupling. We present a new mechanism of attractive potential between electrons, mediated by emergent gauge fields (vacuum or holon) in the strongly correlated mixed valence compounds. In the strong coupling limit, localized electron sites are protected from double occupancy, which results in an emergent holon guage fields. The holon states can, however, attract conduction electrons through valence fluctuation channel, and the resulting doubly occupied states with local and conduction electrons {\it condensate} as Cooper pairs with onsite, fixed-sign, $s$-wave pairing symmetry. We develop the corresponding self-consistent theory of superconductivity, and compare the results with experiments. Our theory provides a new mechanism of superconductivity whose applicability extends to the wider class of intermetallic/mixed-valence materials and other flat-band metals.

###### Current status:
Editor-in-charge assigned

### Submission & Refereeing History

Submission 1906.01312v1 on 6 June 2019