S+-+d Wave Multiband Eliashberg Theory For The Iron Pnictides

TL;DR

This paper develops a multiband Eliashberg theory for iron pnictides with s+-+d-wave symmetry, analyzing the critical temperature, order parameter symmetry, and temperature-dependent properties to compare with experimental data.

Contribution

It introduces a numerical solution of s+-+d-wave Eliashberg equations for iron pnictides, revealing symmetry transitions and temperature effects on superconducting properties.

Findings

System exhibits only twofold in-plane symmetry.

Transition from nodal to fully gapped superconductivity with temperature.

Calculated density of states and superfluid density match experimental trends.

Abstract

We calculated the critical temperature in the framework of s+-+d-wave multiband Eliashberg theory. We have solved these equations numerically to see at what values of the input parameters there is a solution with a non-zero critical temperature and what is the symmetry of the order parameter of this solution. For our model we consider the pnictide case with simplifications that allow us to obtain the most general possible information. For selected and representative cases in which the order parameter has s+-+d symmetry, we calculated the superconducting density of states, the temperature dependence of the gaps, and the superfluid density so that comparison with experimental data can be made. Finally, we show that such a system has only a twofold in-plane symmetry and undergoes a transition from nodal to fully gapped with increasing temperature.