Friday, August 10, 2012

1208.1917 (E. Bascones et al.)

Orbital differentiation and the role of orbital ordering in the magnetic
state of Fe superconductors
   [PDF]

E. Bascones, B. Valenzuela, M. J. Calderón
We analyze the metallic (pi,0) antiferromagnetic state of a five-orbital model for iron superconductors. We find that with increasing interactions the system does not evolve trivially from the pure itinerant to the pure localized regime. Instead we find a region with a strong orbital differentiation between xy and yz, which are half-filled gapped states at the Fermi level, and itinerant zx, 3z^2-r^2 and x^2-y^2. Orbital ordering between yz and zx orbitals arises as a consequence of the interplay of the exchange energy in the antiferromagnetic x direction due to yz localization and the kinetic energy gained by the itinerant orbitals along the ferromagnetic y direction with an overall dominance of the kinetic energy gain. We argue that iron superconductors are close to the boundary between the itinerant and the orbital differentiated regimes and that it could be possible to cross this boundary with doping.
View original: http://arxiv.org/abs/1208.1917

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