Similarities between structural distortions under pressure and chemical doping in superconducting BaFe2As2

TL;DR

This study reveals that structural distortions under pressure and chemical doping in BaFe2As2 lead to similar electronic and structural changes, highlighting the importance of lattice modifications over charge doping in inducing superconductivity.

Contribution

It demonstrates that pressure-induced structural changes in BaFe2As2 mimic those caused by chemical doping, emphasizing the role of lattice distortions in superconductivity.

Findings

Structural features evolve similarly under pressure and doping.

Electronic structure changes are comparable in both cases.

Structural distortions are more crucial than charge doping for superconductivity.

Abstract

The discovery of a new family of high Tc materials, the iron arsenides (FeAs), has led to a resurgence of interest in superconductivity. Several important traits of these materials are now apparent, for example, layers of iron tetrahedrally coordinated by arsenic are crucial structural ingredients. It is also now well established that the parent non-superconducting phases are itinerant magnets, and that superconductivity can be induced by either chemical substitution or application of pressure, in sharp contrast to the cuprate family of materials. The structure and properties of chemically substituted samples are known to be intimately linked, however, remarkably little is known about this relationship when high pressure is used to induce superconductivity in undoped compounds. Here we show that the key structural features in BaFe2As2, namely suppression of the tetragonal to orthorhombic phase transition and reduction in the As-Fe-As bond angle and Fe-Fe distance, show the same behavior under pressure as found in chemically substituted samples. Using experimentally derived structural data, we show that the electronic structure evolves similarly in both cases. These results suggest that modification of the Fermi surface by structural distortions is more important than charge doping for inducing superconductivity in BaFe2As2.