談話会・セミナー

第3回 物理工学科教室談話会 (講師:Dr. Ansgar Liebsch)
2009.11.26

日 時:平成21年11月26日(木)午後2時から
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

Abstract:
The role of Coulomb correlations in the iron pnictide LaFeAsO is studied by generalizing exact diagonalization dynamical mean field theory to five orbitals.[1] 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.[2] 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, arXiv:0911.1940 submitted to PRB
[2] A. Liebsch and N.H. Tong, Phys. Rev. B 80, 165123 (2009)

紹介教員 今田正俊教授・有田亮太郎准教授

第3回物工談話会ご案内(PDF)

談話会・セミナーのトップに戻る