Non-Fermi-liquid behavior in a heavy-fermion alloy at a magnetic instability

The specific heat C and electrical resistivity {ρ} of the heavy-fermion alloy CeCu5.9{Au}0.1exhibit non-Fermi-liquid behavior well below 1 K, i.e., C/T∝-ln(T/{T}₀) and ρ={{{ρ}}}₀$+A'T, over more than a decade in temperature T. The magnetic susceptibility {χ} measured in 0.1 T shows a cusp for T{→}0. This behavior is attributed to the proximity to magnetic order: In contrast to CeCu₆, CeCu_6-x{Au}ₓ$ alloys show long-range antiferromagnetic order, with ${T}N→0 for{x}c$=0.1. Hence ${CeCu}5.9Au0.1 is at the edge of a zero-temperature quantum phase transition. In a large magnetic field (B{≥}3 T) Fermi-liquid behavior is recovered.