First-principles study of superconducting Rare-earth doped CaFe2As2

TL;DR

This study uses first-principles calculations to analyze the structural and electronic effects of rare-earth doping in CaFe2As2, predicting phase transitions and their relation to superconductivity.

Contribution

It provides a comprehensive ab-initio analysis of rare-earth doped CaFe2As2, predicting structural trends and pressure-induced phase transitions relevant to superconductivity.

Findings

Transition pressure decreases with electron doping.

Transition pressure increases linearly with ionic size.

Structural trends match experimental observations.

Abstract

We report a systematic and ab-initio electronic structure calculation of Ca0.75 M0.25 Fe2 As2 with M = Ca, Sr, Eu, La, Ce, Pr, Nd, Pm, Sm, Na, K, Rb. The recently reported experimentally observed structural trends in rare earths-doped CaFe2 As2 compounds are successfully predicted and a complete theoretical description of the pressure induced orthorhombic to collapsed tetragonal transition is given. We demonstrate that the transition pressure is reduced by electron doping and rises linearly with the ionic size of the dopants. We discuss the implications of our description for the realization of a superconducting phase.