Direct observation of the influence of the FeAs4 tetrahedron on superconductivity and antiferromagnetic correlations in Sr2VO3FeAs

TL;DR

This study investigates how pressure-induced distortions of FeAs4 tetrahedra in Sr2VO3FeAs affect its superconductivity and magnetic correlations, revealing a direct link between structural changes and electronic properties.

Contribution

It provides the first direct experimental evidence connecting tetrahedral distortion under pressure to suppression of superconductivity and magnetic correlations in Sr2VO3FeAs.

Findings

Superconductivity remains constant below 10 GPa with regular tetrahedra.

Tetrahedral distortion beyond 10 GPa correlates with Tc decreasing to zero.

Band structure calculations show distortion degrades nesting features and favors antiferromagnetic states.

Abstract

We measure the pressure dependence of the electrical resistivity and the crystal structure of iron superconductor Sr2VO3FeAs. Below ~10 GPa the structure compresses but remains undeformed, with regular FeAs4 tetrahedrons, and a constant Tc. Beyond 10GPa, the tetrahedron strongly distorts, while Tc goes gradually to zero. Band structure calculations of the undistorted structure show multiple nesting features that hinder the development of an antiferromagnetic ground state (AF), allowing the appearance of superconductivity. The deformation of the tetrahedra that breaks band degeneracy degrades multiple nesting, thus favouring one particular AF state at the expense of Tc.