Sr$_{2}$VO$_{3}$FeAs as Compared to Other Fe-based Superconductors

TL;DR

This paper demonstrates that the complex Fermi surface of Sr$_{2}$VO$_{3}$FeAs does not contradict existing theories of Fe-based superconductor superconductivity, as the Fe-derived states still support the quasi-nesting spin-fluctuation model.

Contribution

The study shows that the apparent complexity of the Fermi surface in Sr$_{2}$VO$_{3}$FeAs is due to V states, and when considering Fe-character weighted susceptibility, the quasi-nesting model remains valid.

Findings

The complex Fermi surface is due to V-derived electronic states.

Weighted susceptibility supports the quasi-nesting spin-fluctuation model.

Sr$_{2}$VO$_{3}$FeAs conforms to existing superconductivity theories.

Abstract

One of the most popular scenarios for the superconductivity in Fe-based superconductors (FeBSC) posits that the bosons responsible for electronic pairing are spin-fluctuations with a wave vector spanning the hole Fermi surfaces (FSs) near $\Gamma$ and the electron FSs near M points. So far all FeBSC for which neutron data are available do demonstrate such excitations, and the band structure calculations so far were finding quasi-nested FSs in all FeBSC, providing for a peak in the spin susceptibility at the desired wave vectors. However, the newest addition to the family, Sr$_{2}$VO$_{3}$FeAs, has been calculated to have a very complex FS with no visible quasi-nesting features. It was argued therefore that this material does not fall under the existing paradigm and calls for revisiting our current ideas about what is the likely cause of superconductivity in FeBSC. In this paper, I show that the visible complexity of the FS is entirely due to the V-derived electronic states. Assuming that superconductivity in Sr$_{2}$VO$_{3}$FeAs, as in the other FeBSC, originates in the FeAs layers, and the superconducting electrons are sensitive to the susceptibility of the FeAs electronic subsystem, I recalculate the bare susceptibility, weighting the electronic states with their Fe character, and obtain a susceptibility that fully supports the existing quasi-nesting model.