The driving mechanism of the d-wave orbital order in the iron-based superconductors

TL;DR

This paper investigates the origin and form of orbital order in the electronic nematic phase of iron-based superconductors, revealing that d-wave orbital order is energetically favored due to magnetic correlations, unlike other orbital orders.

Contribution

It demonstrates that the magnetic correlation energy favors the spontaneous emergence of d-wave orbital order in IBSs, providing insight into the nematic phase mechanism.

Findings

D-wave orbital order improves magnetic correlation energy.

On-site and extended s-wave orders are energetically disfavored.

Hund's rule coupling and magnetic patterns influence orbital order stability.

Abstract

We study the driving mechanism and the form of the orbital order in the electronic nematic phase of the iron-based superconductors(IBSs) within the random phase approximation of a 5-band model. We find the magnetic correlation energy of the system can be significantly improved when an orbital order of the d-wave form is spontaneously generated. On the other hand, the magnetic correlation energy increases as one introduce either an on-site or an extended s-wave orbital order. More specifically, we find that the on-site orbital order is disfavored by the Hund's rule coupling and the extended s-wave orbital order is disfavored by the stripy magnetic correlation pattern in the IBSs.