NON-FERMI-LIQUID BEHAVIOR IN A HEAVY-FERMION ALLOY AT A MAGNETIC INSTABILITY

The specific heat C and electrical resistivity rho of the heavy-fermio n alloy CeCu5.9Au0.1 exhibit non-Fermi-liquid behavior well below 1 K, i.e., C/T (is-proportional-to) - ln(T/T0) and rho=rho0 + A'T, over mo re than a decade in temperature T. The magnetic susceptibility chi mea sured in 0.1 T shows a cusp for T --> 0. This behavior is attributed t o the proximity to magnetic order: In contrast to CeCu6, CeCu6-xAux al loys show long-range antiferromagnetic order, with T(N) --> 0 for x(c) = 0.1. Hence CeCu5.9Au0.1 is at the edge of a zero-temperature quantu m phase transition. In a large magnetic field (B greater-than-or-equal -to 3 T) Fermi-liquid behavior is recovered.