Competition between Quadrupole and Magnetic Kondo Effects in Non-Kramers Doublet Systems

Abstract

We discuss possible competition between magnetic and quadrupole Kondo effects in non-Kramers doublet systems under cubic symmetry. The quadrupole Kondo effect leads to non-Fermi-liquid (NFL) ground state, while the magnetic one favors ordinary Fermi liquid (FL). In terms of the $j$-$j$ coupling scheme, we emphasize that the orbital fluctuation must develop in the vicinity of the NFL-FL boundary. We demonstrate a change of behavior in the f-electron entropy by the Wilson's numerical renormalization-group (NRG) method on the basis of the extended two-channel Kondo exchange model. We present implications to extensively investigated PrT${}_2$X${}_{20}$ (T=Ti, V, Ir; X=Al, Zn) systems that exhibit both quadrupole ordering and peculiar superconductivity. We also discuss the magnetic-field effect which lifts weakly the non-Kramers degeneracy. Our model also represents the FL state accompanied by a free magnetic spin as a consequence of stronger competition between the magnetic and the quadrupole Kondo effects.

10 pages, 5 figures, SCES2014 conference proceedings

References in corpus (4)

• The numerical renormalization group method for quantum impurity systems
• Heavy Fermion Superconductivity in the Quadrupole Ordered State of PrV2Al20
• Resolution of Entropy $\ln \sqrt{2}$ by Ordering in Two-Channel Kondo Lattice
• Giant overlap between the magnetic and superconducting phases of CeAu2Si2 under pressure

Cited by in corpus (2)

• Quadrupole-Driven Non-Fermi Liquid and Magnetic-Field Induced Heavy Fermion States in a Non-Kramers Doublet System
• Thermal and field-induced transitions in ferroquadrupolar Kondo systems