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Phys. Rev. B 53, R8828–R8831 (1996)

Spin and charge gaps in the one-dimensional Kondo-lattice model with Coulomb interaction between conduction electrons

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Naokazu Shibata
Institute for Solid State Physics, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106, Japan and Department of Physics, Faculty of Science, Science University of Tokyo, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162, Japan

Tomotoshi Nishino
Department of Physics, Graduate School of Science, Tohoku University, Sendai 980, Japan

Kazuo Ueda
Institute for Solid State Physics, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106, Japan

Chikara Ishii
Department of Physics, Faculty of Science, Science University of Tokyo, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162, Japan

Received 26 December 1995; published in the issue dated 1 April 1996

The density-matrix renormalization-group method is applied to the one-dimensional Kondo-lattice model with the Coulomb interaction between the conduction electrons. The spin and charge gaps are calculated as a function of the exchange constant J and the Coulomb interaction Uc. It is shown that both the spin and charge gaps increase with increasing J and Uc. The spin gap vanishes in the limit of J→0 for any Uc with an exponential form, Δs∝exp[-1/α(Uc)Jρ]. The exponent, α(Uc), is determined as a function of Uc. The charge gap is generally much larger than the spin gap. In the limit of J→0, the charge gap vanishes as Δc=1/2J for Uc=0 but for a finite Uc it tends to a finite value, which is the charge gap of the Hubbard model.

© 1996 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.53.R8828
DOI:
10.1103/PhysRevB.53.R8828
PACS:
 
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