Interplay between magnetism and superconductivity in Fe-pnictides

TL;DR

This paper investigates the phase transitions and coexistence of magnetic and superconducting orders in iron pnictides, revealing conditions under which these states compete or coexist, especially highlighting the role of incommensurate SDW order.

Contribution

It provides a theoretical analysis of phase transitions and coexistence of SDW magnetism and $s^+$ superconductivity in a two-band model of iron pnictides, emphasizing the incommensurate SDW state.

Findings

Transition between SDW and superconductivity can be first order or involve coexistence.

Coexistence of orders is possible when SDW is incommensurate.

The nature of the phase transition depends on model parameters.

Abstract

We consider phase transitions and potential co-existence of spin-density-wave (SDW) magnetic order and extended s-wave ($s^+$) superconducting order within a two-band itinerant model of iron pnictides, in which SDW magnetism and $s^+$ superconductivity are competing orders. We show that depending on parameters, the transition between these two states is either first order, or involves an intermediate phase in which the two orders co-exist. We demonstrate that such co-existence is possible when SDW order is incommensurate.