Origin Of non-Fermi Liquid Behavior Research Articles

Understanding the origin of non-Fermi liquid behaviour in doped Kondoinsulators

We have made inelastic neutron scattering measurements on the doped Kondo insulators Ce(Rh0.8Pd0.2)Sband (Ce0.7Th0.3)RhSb.Previous bulk property measurements showed non-Fermi liquid (NFL) behaviour forboth compositions. In our inelastic neutron scattering data these two compounds alsoshow E/Tscaling behaviour in the dynamical spin susceptibility with different exponents,which is considered a characteristic feature of NFL systems. We discuss howthese two different exponents might be related to different microscopicmechanisms of the NFL behaviour in the bulk properties as well as theE/Tscaling behaviour seen in the dynamical susceptibility.

μ+SR observation of magnetic ordering and non-Fermi liquid scaling in CeCoGe 1.8Si 1.2

Muon spin relaxation investigations of CeCoGe 1.8Si 1.2, which is close to a quantum critical concentration, show magnetic ordering in a volume fraction of ∼50% with a transition temperature of ∼0.5 K. The zero-field relaxation rate λ f of this fraction exhibits a power law of temperatures between 0.7 and 1 K, where the specific heat to temperature ratio ( C/ T) scales with log T , and possibly demonstrate non-Fermi liquid (NFL) scaling. We suggest that the disorder which introduces inhomogenities in Kondo temperatures and RKKY coupling strengths of Ce ions as a possible origin of NFL behaviour in this alloy.

NMR and studies of non-Fermi-liquid behaviour in disordered heavy-fermion systems

Evidence has emerged from nuclear magnetic resonance (NMR) and muon spin-rotation experiments that non-Fermi-liquid (NFL) behaviour in heavy-fermion alloys can in some cases be due to an inhomogeneous distribution of Kondo temperatures arising from disorder in the random alloy. Such `Kondo disorder' implies a broad distribution of the heavy-fermion spin polarization, which is reflected in the widths of NMR and lines. A simple model for the shape and width of the distribution of accounts for the temperature and field dependence of the bulk susceptibility in the NFL alloys , x = 1.0 and 1.5, and then agrees with NMR values of the width of the susceptibility distribution with no further adjustable parameters. Comparison of NMR and estimates of indicates that the susceptibility is disordered on an atomic length scale. In contrast, lines in are too narrow for Kondo disorder to account for NFL properties unless, as seems unlikely, the correlation length is long in this alloy. Similarly, small low-temperature NMR linewidths make it unlikely that Kondo disorder is the origin of NFL behaviour in .