Spectral density in a nematic state of iron pnictides

Abstract

Using cluster-perturbation theory, we calculate the spectral density A(k,w) for a nematic phase of models describing pnictide superconductors, where very short-range magnetic correlations choose the ordering vector (pi,0) over the equivalent (0,pi) and thus break the fourfold rotation symmetry of the underlying lattice without inducing long-range magnetic order. In excellent agreement with angle resolved photo-emission spectroscopy (ARPES), we find that the yz bands at X move to higher energies. When onsite Coulomb repulsion brings the system close to a spin--density-wave (SDW) and renormalizes the band width by a factor of approx. 2, even small anisotropic couplings of 10 to 15 meV strongly distort the bands, splitting the formerly degenerate states at X and Y by approx. 70 meV and shifting the yz states at X above the chemical potential. This similarity to the SDW bands is in excellent agreement with ARPES. An important difference to the SDW bands is that the yz bands still cross the Fermi level, again in agreement with experiment. We find that orbital weights near the Fermi surface provide a better characterization than overall orbital densities and orbital polarization.

Fixed mistakes in the Hamiltonian given (the one used in the calculations was correct); accepted for PRB

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• The ab initio study of unconventional superconductivity in CeCoIn${}_5$ and FeSe
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• Tunneling spectroscopy for probing orbital anisotropy in iron pnictides
• Multiple phase transitions in Pauli limited iron-based superconductors
• Localization and Orbital Selectivity in Iron-Based Superconductors with Cu Substitution
• Orbital Nematic Order and Interplay with Magnetism in the Two-Orbital Hubbard Model
• Mechanism of hole propagation in the orbital compass models
• Unconventional superconductivity in iron-base superconductors in a three-band model
• Breaking of four-fold lattice symmetry in a model for pnictide superconductors
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