Decoding 122-Type Iron-Based Superconductors: A Comprehensive Simulation of Phase Diagrams and Transition Temperatures

TL;DR

This paper presents a comprehensive simulation model for 122-type iron-based superconductors, integrating multiple theoretical approaches and experimental data to accurately predict phase diagrams and transition temperatures under various conditions.

Contribution

It introduces an innovative combined modeling approach that incorporates experimental ARPES data and predicts superconducting behavior across different compounds and pressures.

Findings

Calculated Tc values closely match experimental data.

MgFe2As2 remains non-superconducting under pressure.

Model effectively predicts phase diagrams at high pressure.

Abstract

Iron-based superconductors, a cornerstone of low-temperature physics, have been the subject of numerous theoretical models aimed at deciphering their complex behavior. In this study, we present a comprehensive approach that amalgamates several existing models and incorporates experimental data to simulate the superconducting phase diagrams of the principal 122-type iron-based compounds. Our model considers a multitude of factors including the momentum dependence of the superconducting gap, spin-orbital coupling, antiferromagnetism, spin density wave, induced XY potential on the tetrahedral structure, and electron-phonon coupling. We have refined the electron-phonon scattering matrix using experimental angle-resolved photoemission spectroscopy (ARPES) data, ensuring that all electrons pertinent to iron-based superconductivity are accounted for. This innovative approach allows us to calculate theoretical critical temperature Tc values for Ba1-xKxFe2As2, CaFe2As2 and SrFe2As2 as functions of pressure. These calculated values exhibit remarkable agreement with experimental findings. Furthermore, our model predicts that MgFe2As2 remains non-superconducting irrespective of the applied pressure. Given that 122-type superconductivity at low pressure or low doping concentration has been experimentally validated, our combined model serves as a powerful predictive tool for generating superconducting phase diagrams at high pressure. This study underscores that the high transition temperatures and the precise doping and pressure dependence of iron-based superconductors are intrinsically linked to an intertwined mechanism involving a strong interplay between structural, magnetic and electronic degrees of freedom.