2004/10/05 by Winfried Koller, A. C. Hewson, Alex C. Hewson +2 · 4 citations
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.72.045117
14 pages, 19 figures
arxiv created 2004/10/05 · openalex publication_date 2005/07/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We give a comprehensive analysis of the singular dynamics and of the low-energy fixed point of one-channel impurity s\text\ensuremath-d models with ferromagnetic and underscreened antiferromagnetic couplings. We use the numerical renormalization group (NRG) to perform calculations at T=0. The spectral densities of the one-electron Green's functions and t-matrices are found to have very sharp cusps at the Fermi level (\ensuremathω=0), but do not diverge. The approach of the Fermi level is governed by terms proportional to 1∕ln2(\ensuremathω∕T0) as \ensuremathω\ensuremath→0. The scaled NRG energy levels show a slow convergence as 1∕(N+C) to their fixed point values, where N is the iteration number and C is a constant dependent on the coupling J from which the low energy scale T0 can be deduced, with a renormalized coupling \stackrel\ifmmode \else \~\fiJ(\ensuremathω)=1∕ln(\ensuremathω∕T0). We calculate also the dynamical spin susceptibility, and the elastic and inelastic scattering cross sections as a function of \ensuremathω. The inelastic scattering goes to zero as \ensuremathω\ensuremath→0, as expected for a Fermi liquid, but anomalously slowly compared to the fully screened case. We obtain the asymptotic forms for the phase shifts for elastic scattering of the quasiparticles in the high-spin and low-spin channels. The asymptotic forms found for the one-electron Green's functions and t-matrices do not simply correspond to a perturbation expansion in powers of \stackrel\ifmmode \else \~\fiJ(\ensuremathω).