Crossover between Fermi Liquid and non-Fermi Liquid in Orbitally Degenerate Kondo Systems

Abstract

Entanglement of spin and orbital Kondo effect is investigated on the basis of a Kondo-type exchange model with twofold orbital degeneracy. By using Wilson's numerical renormalization-group method, we examine dynamical and thermal properties respecting the difference in time-reversal property of multipole operators. In the presence of particle-hole symmetry, the model has a new non-Fermi-liquid fixed point with a fractional entropy. The spectral intensity of the quadrupole susceptibility diverges in the zero-frequency limit, while the dipole susceptibility shows a Fermi-liquid-like behavior. This is understood by mapping to the two-channel Kondo model, in which the dipole moment is mapped onto the operators with the scaling dimension ${\Delta }_m=1$, while the quadrupole moment onto the operators with another scaling dimension ${\Delta }_e=1/2$. Even for a fairly particle-hole asymmetric case with the Fermi-liquid ground state, the non-Fermi-liquid behavior has significant influences in electric and thermal properties.

7 pages, 9 figures, to appear in J. Phys Soc. Jpn. Vol. 68 No. 12, title changed and some corrections made

References in corpus (8)

• SU(4) Theory for Spin Systems with Orbital Degeneracy
• SU(4) spin-orbit critical state in one dimension
• Thermodynamics of the one-dimensional SU(4) symmetric spin-orbital model
• Fluctuation Effects on the Quadrupolar Ordering in Magnetic Field
• Perturbative renormalization of multi-channel Kondo-type models
• Orbital Kondo Effect in Ce${}_x$La${}_{1-x}$B${}_6$: Scaling Analysis
• An Extended Anderson Model that shows Decreasing Resistivity with Decreasing Temperature
• Charge Kondo effect toward a non-Fermi-liquid fixed point in the orbitally degenerate exchange model

Cited by in corpus (2)

• The numerical renormalization group method for quantum impurity systems
• Critical Nature of Non-Fermi Liquid in Spin 3/2 Multipolar Kondo Model