© 2015 American Physical Society. We present a comparative calculation of the electronic structure of the high critical temperature superconductor Co-doped BaFe2As2 and its parent compound at the electron correlation level by the embedded cluster method; the electron correlation is calculated through the second-order Møller-Plesset perturbation theory. The superconducting doped material is represented by the Ba4CoFe4As8 cluster. The analysis of the orbital populations in this cluster reveals the formation of an antiferromagnetic order in the Fe plane with a spin-density increase on the central Co atom with respect to the spin density of the central Fe atom of the undoped case. This increase is associated with an increase of the dz2 orbital population of the central atom. However, the formation mechanism of the local magnetic moment implies also a spin transfer from the nearest-neighbor Fe atoms and from the next-nearest-neighbor As atoms to the central Co atom, and it corresponds to a J1-J2 antiferromagnetic Heisenberg model. Some particular features of dyz and dx2-y2 orbitals in the triplet and in the singlet cluster states are interpreted to correspond to a spinless fermion. This result, as well as the result relative to the formation mechanism of the magnetic moments, can be connected with a model of resonating-valence-bond (RVB) superconductors suggested recently by Poilblanc et al. [Phys. Rev. B 89, 241106 (2014)PRBMDO1098-012110.1103/PhysRevB.89.241106] and based on the Anderson RVB theory.
|Idioma original||Inglés estadounidense|
|Publicación||Physical Review B - Condensed Matter and Materials Physics|
|Estado||Publicada - 28 may 2015|