An investigation of the interrelationship between pressure and correlation in LaFeAsO under pressure

TL;DR

This study explores how pressure influences electronic correlations in LaFeAsO using advanced computational methods, revealing orbital-specific charge transfer and a correlation-driven switch in superconducting transition temperature.

Contribution

It provides new insights into the pressure-dependent orbital behavior and correlation effects in LaFeAsO, highlighting the orbital switching mechanism affecting superconductivity.

Findings

Charge transfer occurs between Fe-3d orbitals under pressure.

The Fe-3dxy orbital plays a crucial role in superconductivity.

A transition between high and low Tc states is driven by correlation changes.

Abstract

Here, we investigated the interrelationship between pressure and correlation in the LaFeAsO compound by the density functional theory method combined with the dynamical mean field theory (DFT+DMFT) method. The spectral function and the occupation number (ON) of Fe-3d orbitals at different pressures were extracted from the calculations, and the importance of the role of correlation in superconductivity in iron-based compounds was indicated. The measured ON of Fe-3d orbitals demonstrated charge transfer between them and also the crucial role of the Fe-3dxy (xy) orbital in superconductivity in these materials. A switching behavior between high and low TC through decreasing the correlation was observed in our calculations, originating from the orbital switching. This shows the significant role of the orbital degrees of freedom in iron-based superconductors.