Thermal and Dynamical Properties of the Two-band Hubbard Model Compared with FeSi

Abstract

We study the two-band Hubbard model introduced by Fu and Doniach as a model for FeSi which is suggested to be a Kondo insulator. Using the self-consistent second-order perturbation theory combined with the local approximation which becomes exact in the limit of infinite dimensions, we calculate the specific heat, the spin susceptibility and the dynamical conductivity and point out that the reduction of the energy gap due to correlation is not significant in contrast to the previous calculation. It is also demonstrated that the gap at low temperatures in the optical conductivity is filled up at a rather low temperature than the gap size, which is consistent with the experiment.

6 pages, LaTeX, 7 PS figures included, uses RevTeX

References in corpus (2)

• Self-consistent perturbational study of insulator-to-metal transition in Kondo insulators due to strong magnetic field
• Optical phonons in the reflectivity spectrum of FeSi

Cited by in corpus (5)

• Metal-insulator transition and magnetism in correlated band insulator: FeSi and Fe${}_{1-x}$Co${}_x$Si
• Correlation Effects on Optical Conductivity of FeSi
• Suppressed reflectivity due to spin-controlled localization in a magnetic semiconductor
• Correlated excited states in the narrow gap band semiconductor FeSi and antiferromagnetic screening of local spin moments
• Microscopic model for the semiconductor-to-ferromagnetic-metal transition in FeSi${}_{1-x}$Ge${}_x$ Alloys