English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The pairing mechanism and gap structure in Ba122 pnictides have been hotlydiscussed for long time as one of the central issues in Fe-basedsuperconductors. Here, we attack this problem by taking account of the vertexcorrections (VCs) for the Coulomb interaction $U$ ($U$-VCs), which are totallydropped in conventional Migdal-Eliashberg formalism. The $U$-VC in the chargesusceptibility induces strong orbital fluctuations, and the $U$-VC alsoenlarges the orbital-fluctuation-mediated attractive interaction. By analyzingthe effective multiorbital Hubbard model for Ba122 pnictides, we find that theorbital fluctuations develop in all four $d$-orbitals ($t_{2g}$- and$z^2$-orbitals), by which the FSs are composed. For this reason, nearlyisotropic gap function appears on all the hole-type FSs, including the outerhole-FS around Z-point composed of $z^2$-orbital. In contrast, nodal gapstructure appears on the electron-type FSs for wide parameter range. Theobtained nodal $s$-wave state changes to fully-gapped $s$-wave state withoutsign-reversal ($s_{++}$-wave state) by introducing small amount of impurities,accompanied by small reduction in $T_c$. The present microscopic theorynaturally explains the important characteristics of the gap structure of bothhole- and electron-FSs in Ba122 pnictides, without introducing anyphenomenological pairing interaction.

Pairing mechanism for nodal $s$-wave superconductivity in BaFe$_2$(As,P)$_2$: Analysis beyond Migdal-Eliashberg formalism