1206.0801 (Z. P. Yin et al.)

Fractional powerlaws and the nature of the incoherent states in iron
chalcogenides and ruthenates    [PDF]

Z. P. Yin, K. Haule, G. Kotliar

Fractional powerlaws are known to occur in the optical conductivity of ruthenates. We find similar phenomena in the iron chalcogenides, and trace its origin to the Hund's rule interaction. At low energy these materials become Fermi liquids but with very low coherent temperature, while at finite temperature we find incoherent electronic states. Upon raising the temperature incoherence occurs first in the $xy$ orbital, which makes some bands almost invisible to angle-resolved photoemission spectroscopy measurements at finite temperatures. A simplified Hubbard model captures the fractional powerlaw trends of the first principles calculations. We derive a low energy Hamiltonian of a simplified SU(3)$\times$SU(2) case and demonstrate that a strong Hund's rule interaction leads to a ferromagnetic spin-spin Kondo interaction, which can result in a non-Fermi liquid physics of unquenched spins.

View original: http://arxiv.org/abs/1206.0801