Schedule Feb 12, 2010
Fermi-Liquid, Non-Fermi-Liquid, and Mott Phases in Iron Pnictides and Cuprates
Ansgar Liebsch (Research Ctr Juelich)

The role of Coulomb correlations in LaFeAsO is studied by generalizing exact diagonalization dynamical mean field theory to five orbitals [1]. For rotationally invariant Hund coupling a spin freezing transition from a paramagnetic Fermi-liquid to a non-Fermi-liquid metallic phase is found at U = 3 eV, J = 0.75 eV. For Ising exchange, this transition occurs at about U = 2 eV.

The correlation-induced scattering rate as a function of doping relative to half-filling, delta=n/5-1, where n=6 for the undoped material, is shown to be similar to the one in the two-dimensional single-band Hubbard model.

In this scenario, the parent Mott insulator of LaFeAsO is the half-filled n=5 limit, while the undoped n=6 material corresponds to the critical doping region delta_c ~ 0.2 in the cuprates, on the verge between the Fermi-liquid phase of the overdoped region and the non-Fermi-liquid pseudogap phase in the underdoped region.

[1] H. Ishida and A. Liebsch, Phys. Rev. B 81, xxx (2010).

Author entry (protected)