Systematic composition dependence in YbCu5-xAux from dense Kondo to antiferromagnetic system through quantum critical point around x=0.2-0.4

Temperature and magnetic field variations of the electric resistivitiy (rho ) as well as temperature dependence of the magnetic susceptibility (chi) ar e reported for the YbCu5-chiAuchi system with the C15b-type structure. Thes e results indicate a systematic composition dependence from dense Kondo to RKKY antiferromagnetic system via quantum critical point with x=0.2-0.4. Th e logarithmic temperature dependence of rho was observed in the middle temp erature range for all the compositions, implying that the incoherent Kondo scattering is dominant in this T-region. With decreasing temperature, the p tends to saturate, makes a maximum, then decreases toward the Fermi liquid ground state due to the coherent dense Kondo effect (x<0.2), or toward the antiferromagnetic ground state due to the RKKY interaction (for x>0.4). Th e non-Fermi liquid behavior was observed around the quantum critical compos ition (x=0.2-0.4). (C) 2001 Elsevier Science B.V. All rights reserved.