Coherence Scale of the Kondo Lattice

Abstract

It is shown that the large-N approach yields two energy scales for the Kondo lattice model. The single-impurity Kondo temperature, TK, signals the onset of local singlet formation, while Fermi liquid coherence sets in only below a lower scale, T ⋆ . At low conduction electron density nc ("exhaustion" limit) , the ratio T ⋆ /TK is much smaller than unity, and is shown to depend only on nc and not on the Kondo coupling. The physical meaning of these two scales is demonstrated by computing several quantities as a function of nc and temperature.

Theory of the Kondo Lattice: Competition Between Kondo Effect and Magnetic Order

“…(4) gives T K depending on the band filling as n(2 − n), which is consistent with a √ n dependence when n → 0, as found in Ref. [20].…”

Orbital state and magnetic properties ofLiV2O4

“…41 Singh et al 42 50 The competition between the Kondo effect and frustrating exchange interactions in a Kondo-lattice model within a large-N approach for the spin liquid together with dynamical mean-field theory were studied by Burdin et al. 51 Despite all this theoretical effort, there does not yet exist an undisputed microscopic explanation of the HF behavior of LiV 2 O 4 at low temperatures. It has been attempted to explain the low-temperature properties of LiV 2 O 4 by a mechanism analogous to one for systems with local moments on a pyrochlor lattice, which are frustrated with respect to the antiferromagnetic interactions.…”

Fractionalized Fermi Liquids

“…For simplicity, we restrict our attention here to nonmagnetic states, in which there is no average static moment on any site ( S j = 0), and the spin rotation invariance of the Hamiltonian is preserved: the S j moments have been 'screened', either by the c σ conduction electrons, or by their mutual interactions (there is a natural extension of our results to magnetic states). It is widely accepted [1,[3][4][5][6][7] that such a ground state of H is a conventional Fermi liquid (FL) with a Fermi surface of 'heavy' quasiparticles, enclosing a volume, V F L determined by the Luttinger theorem:…”