Tuning of Non-Fermi-Liquid Behavior with Pressure

Abstract

The Néel temperature of the antiferromagnetic heavy-fermion alloy Ce${\mathrm{Cu}}_{5.7}$ ${\mathrm{Au}}_{0.3}$ ($T_N=0.49\mathrm{}$ K for $p=0\mathrm{}$) can be continuously tuned to zero with increasing hydrostatic pressure $p$. At $p=p_c$ where $T_N=0\mathrm{}$ is reached, the specific heat $C$ varies as $\frac{C}{T}\sim -\ln \left(\frac{T}{T_0}\right)$ between 0.1 and 2 K, indicative of non-Fermi-liquid behavior. The observed linear $T_N\mathrm{}\left(p\right)\mathrm{}$ dependence puts rigorous constraints on theories for a quantum phase transition at $T=0\mathrm{}$ between magnetic and nonmagnetic ground states.