第3回 物理工学科教室談話会 （講師：Dr. Ansgar Liebsch）
|場 所||工６号館 ３階 セミナー室Ａ|
|講演者||Prof. Dr. Ansgar Liebsch (Research Center Juelich)|
|題 目||Fermi-liquid, non-Fermi-liquid, and Mott phases in iron pnictides and cuprates|
The role of Coulomb correlations in the iron pnictide LaFeAsO is studied by generalizing exact diagonalization dynamical mean field theory to five orbitals. For rotationally invariant Hund’s rule coupling a continuous transition from a paramagnetic Fermi-liquid phase to a non-Fermi-liquid metallic phase exhibiting frozen moments is found at moderate Coulomb energies. For Ising-like exchange, this transition is first order and occurs at a lower critical Coulomb energy. The correlation-induced scattering rate as a function of doping relative to half-filling, i.e., delta=n/5-1, where n=6 for the undoped material, is shown to be qualitatively 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.
 H. Ishida and A. Liebsch, arXiv:0911.1940 submitted to PRB
 A. Liebsch and N.H. Tong, Phys. Rev. B 80, 165123 (2009)