Magnetism and superconductivity in the layered hexagonal transition metal pnictides

TL;DR

This study explores the electronic and magnetic properties of hexagonal transition-metal pnictides, revealing their similarities to iron-based superconductors and predicting potential unconventional superconducting states upon doping.

Contribution

It provides a theoretical analysis of magnetic interactions in hexagonal pnictides, suggesting they could host novel superconducting states similar to those in iron-based superconductors.

Findings

NNN AFM couplings are maximized in these materials.

Hexagonal pnictides are highly frustrated magnetic systems.

Potential for time-reversal symmetry broken $d+id$ superconductivity upon doping.

Abstract

We investigate the electronic and magnetic structures of the 122 (AM$_2$B$_2$) hexagonal transition-metal pnictides with A=(Sr, Ca), M=(Cr, Mn, Fe, Co, Ni) and B=(As, P, Sb). It is found that the family of materials share critical similarities with those of tetragonal structures that include the famous iron-based high temperature superconductors. In both families, the next nearest neighbor(NNN) effective antiferromagnetic(AFM) exchange couplings reach the maximum value in the iron-based materials. While the NNN couplings in the latter are known to be responsible for the C-type AFM state and to result in the extended s-wave superconducting state upon doping, they cause the former to be extremely frustrated magnetic systems and can lead to an time reversal symmetry broken $d+id$ superconducting state upon doping. The iron-based compounds with the hexagonal structure, thus if synthesized, can help us to determine the origin of high temperature superconductivity.