Effect of anisotropy in the $S=1$ underscreened Kondo lattice

Abstract

We study the effect of crystal field anisotropy in the underscreened $S=1$ Kondo lattice model. Starting from the two orbital Anderson lattice model and including a local anisotropy term, we show, through Schrieffer-Wolff transformation, that local anisotropy is equivalent to an anisotropic Kondo interaction ($J_{\parallel }\ne J_{\perp }$). The competition and coexistence between ferromagnetism and Kondo effect in this effective model is studied within a generalized mean-field approximation. Several regimes are obtained, depending on the parameters, exhibiting or not coexistence of magnetic order and Kondo effect. Particularly, we show that a re-entrant Kondo phase at low temperature can be obtained. We are also able to describe phases where the Kondo temperature is smaller than the Curie temperature ($T_K<T_C$). We propose that some aspects of uranium and neptunium compounds that present coexistence of Kondo effect and ferromagnetism, can be understood within this model.

arXiv comment7 pages, 3 figures

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Cited by in corpus (5)

• Ground-state phase diagram of the $S=1$ one-dimensional Kondo lattice model with a uniaxial anisotropy under transverse fields
• Heavy quasiparticle bands in the underscreened quasiquartet Kondo lattice
• Metamagnetic transition in the two $f$ orbitals Kondo lattice model
• Optical and magnetic excitations in the underscreened quasi-quartet Kondo lattice
• On the Problem of Validity of Anderson and Kondo Models in Physics of Strongly Correlated Electron Systems