Three orbital model for the iron-based superconductors

By M. Daghofer, Andrew D Nicholson, A. Moreo, E. Dagotto. 2009

137 citations recorded by the source corpus.

The theoretical need to study the properties of the Fe-based high-Tc superconductors using reliable manybody techniques has highlighted the importance of determining what is the minimum number of orbital degrees of freedom that will capture the physics of these materials. While the shape of the Fermi surface FS obtained with the local-density approximation LDA can be reproduced by a two-orbital model, it has been argued that the bands that cross the chemical potential result from the strong hybridization of three of the Fe 3d orbitals. For this reason, a three orbital Hamiltonian for LaOFeAs obtained with the Slater-Koster formalism by considering the hybridization of the As p orbitals with the Fe dxz, dyz, and dxy orbitals is discussed here. This model reproduces qualitatively the FS shape and orbital composition obtained by LDA calculations for undoped LaOFeAs when four electrons per Fe are considered. Within a mean-field approximation, its magnetic and orbital properties in the undoped case are here described for intermediate values of J/U. Increasing the Coulomb repulsion U at zero temperature, four different regimes are obtained: 1 paramagnetic, 2 magnetic ,0 spin order, 3 the same ,0 spin order but now including orbital order, and finally 4 a magneticmore » and orbital ordered insulator. The spin-singlet pairing operators allowed by the lattice and orbital symmetries are also constructed. It is found that for pairs of electrons involving up to diagonal nearest-neighbors sites, the only fully gapped and purely intraband spin-singlet pairing operator is given by k= fkdk,, d k,, with fk=1 or cos kx cos ky which would arise only if the electrons in all different orbitals couple with equal strength to the source of pairing.« less

Subfields: Accounting, Condensed Matter Physics, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/56677386dc3d3ecd1f51a292810a648bc68da1db

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In Accounting

E. Dagotto

In Condensed Matter Physics

In Electronic, Optical and Magnetic Materials

Citations in the corpus

Magnetism and its microscopic origin in iron-based high-temperature superconductors (2012, background): “4, and similar results were reported for the two- and five-orbital models [99].”
Functional renormalization group approach to correlated fermion systems (2011, background): “At least three of the five iron dorbitals have non-negligible weight near the Fermi level (Daghofer et al., 2010; Mazin et al., 2008).”