When either electron or hole doped at concentrations x∼0.1, the LaOFeAs family displays remarkably high temperature superconductivity with Tc up to 55 K. In the most energetically stable QM=(π,π) antiferromagnetic (AFM) phase comprised of tetragonal-symmetry breaking alternating chains of aligned spins, there is a deep pseudogap in the Fe 3d states centered at the Fermi energy, and very strong magnetophonon coupling is uncovered. Doping (of either sign) beyond x∼0.1 results in Fe 3d heavy mass carriers (m∗∼4−8) with a large Fermi surface. Calculated Fe-Fe transverse exchange couplings Jij(R) reveal that exchange coupling is strongly dependent on the AFM symmetry and Fe-As distance.
@article{arxiv.0804.3355,
title = {Electron-Hole Symmetry and Magnetic Coupling in Antiferromagnetic LaOFeAs},
author = {Z. P. Yin and S. Lebègue and M. J. Han and B. Neal and S. Y. Savrasov and W. E. Pickett},
journal= {arXiv preprint arXiv:0804.3355},
year = {2009}
}