2006/05/19 by Avraham Schiller, Schiller, Avraham, Lorenzo De Leo +1
Physics and Astronomy · #FOS: Physical sciences #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Rare-earth and actinide compounds #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.cond-mat/0605474
15 pages, 5 figures
arxiv created 2006/05/19 · openalex publication_date 2006/05/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The phase diagram of the multichannel Kondo Hamiltonian with an XXZ spin-exchange anisotropy is revisited, revealing a far richer fixed-point structure than previously appreciated. For a spin-1/2 impurity and k > 2 conduction-electron channels, a second ferromagnetic-like domain is found deep in the antiferromagnetic regime. The new domain extends above a (typically large) critical longitudinal coupling Jz∗ > 0, and is separated from the antiferromagnetic domain by a second Kosterliz-Thouless line. A similar line of stable ferromagnetic-like fixed points with a residual isospin-1/2 local moment is shown to exist for large Jz >> |J⊥| > 0 and arbitrary k and s obeying |k - 2s| > 1. Here Jz is the longitudinal spin-exchange coupling, J⊥ is the transverse coupling, and s is the impurity spin. Near the free-impurity fixed-point, spin-exchange anisotropy is a relevant perturbation for s > 1/2 and arbitrary k. Depending on the sign of Jz2 - J⊥2 and the parity of 2s, the system flows either to a conventional Fermi liquid with no residual degeneracy, or to a k-channel, spin-1/2 Kondo effect, or to a line of ferromagnetic-like fixed points with a residual isospin-1/2 local moment. These results are obtained through a combination of perturbative renormalization-group techniques, Abelian bosonization, a strong-coupling expansion in 1/Jz, and explicit numerical renormalization-group calculations.