Orbital-weight redistribution triggered by spin order in the pnictides

TL;DR

This study investigates how spin order influences orbital-weight redistribution in iron-based superconductor models, revealing that magnetic order primarily drives the observed orbital and Fermi surface characteristics.

Contribution

It demonstrates that magnetic order, rather than ferro-orbital order, mainly causes orbital-weight redistribution in realistic three- and five-orbital models of pnictides.

Findings

Different magnetizations in xz and yz orbitals observed

Fermi surface predominantly exhibits xz orbital character

Magnetic order drives orbital redistribution more than ferro-orbital order

Abstract

The one-particle spectral function and its orbital composition are investigated in a three-orbital model for the undoped parent compounds of the iron-based superconductors. In the realistic parameter regime, where results best fit experimental data, it is observed that the magnetization in the xz and yz orbitals are markedly different and the Fermi surface presents mostly xz character, as recently observed in photoemission experiments [T. Shimojima et al., Phys. Rev. Lett. 104, 057002 (2010)]. Since the ferro-orbital order in this regime is at most a few percent, these results are mainly driven by the magnetic order. An analogous analysis for a five-orbital model leads to similar conclusions.