Breaking of four-fold lattice symmetry in a model for pnictide superconductors

TL;DR

This paper explores how different mechanisms breaking fourfold lattice symmetry in a three-band model of iron-based superconductors produce similar electronic signatures when strong onsite interactions induce spin-density wave proximity.

Contribution

It compares magnetic couplings, orbital-ordering fields, and anisotropic hoppings in breaking lattice symmetry without long-range order, revealing their similar effects under strong interactions.

Findings

All three symmetry-breaking mechanisms produce similar signatures near the Fermi level.

Band distortions are independent of differences in xz and yz orbital densities.

Strong onsite interactions lead to comparable effects regardless of the symmetry-breaking mechanism.

Abstract

We investigate the interplay of onsite Coulomb repulsion and various mechanisms breaking the fourfold lattice symmetry in a three-band model for the iron planes of iron-based superconductors. Using cluster-perturbation theory allows us to locally break the symmetry between the x- and y-directions without imposing long-range magnetic order. Previously investigated anisotropic magnetic couplings are compared to an orbital-ordering field and anisotropic hoppings. We find that all three mechanisms for a broken rotational symmetry lead to similar signatures once onsite interactions are strong enough to bring the system close to a spin-density wave. The band distortions near the Fermi level are independent of differences between the total densities found in xz and yz orbitals.