CaFe2As2: a Springboard to Investigating Fe-Pnictide Superconductivity

TL;DR

This paper provides detailed electronic structure calculations for CaFe2As2, revealing its unique properties in different phases and discussing their implications for understanding Fe-pnictide superconductivity.

Contribution

It offers new insights into the electronic structure of CaFe2As2, highlighting its strong three-dimensionality and the roles of magnetic and lattice interactions in superconductivity.

Findings

The 'collapsed' tetragonal phase is strongly 3D, unlike other Fe-pnictides.

Magnetic and lattice interactions are both important for superconductivity.

LSDA accurately predicts magnetic moments in the orthorhombic phase.

Abstract

We present detailed electronic structure calculations for CaFe2As2. We investigate in particular the `collapsed' tetragonal and orthorhombic regions of the temperature-pressure phase diagram and find properties that distinguish CaFe2As2 from other Fe-pnictide compounds. In contrast to the tetragonal phase of other Fe-pnictides the electronic structure in the `collapsed' tetragonal phase of CaFe2As2 is found to be strongly 3D. We discuss the influence of these properties on the formation of superconductivity and in particular we find evidence that both magnetic and lattice interactions may be important to the formation of superconductivity. We also find that the Local Spin Density Approximation is able to accurately predict the ordering moment in the low temperature orthorhombic phase.