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Competition between crystalline electric field singlet and itinerant states of f electrons

Shinji Watanabe·Yoshio Kuramoto
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Abstract

A new kind of phase transition is proposed for lattice fermion systems with simplified f^2 configurations at each site. The free energy of the model is computed in the mean-field approximation for both the itinerant state with the Kondo screening, and a localized state with the crystalline electric field (CEF) singlet at each site. The presence of a first-order phase transition is demonstrated in which the itinerant state changes into the localized state toward lower temperatures. In the half-filled case, the insulating state at high temperatures changes into a metallic state, in marked contrast with the Mott transition in the Hubbard model. For comparison, corresponding states are discussed for the two-impurity Kondo system with f^1 configuration at each site.

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Shinji Watanabe, Yoshio Kuramoto. 1997-06-13. Competition between crystalline electric field singlet and itinerant states of f electrons. https://doi.org/10.1007/s002570050487

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