Non-Fermi-liquid behaviour close to the disappearance of ferromagnetism in CePd_1−<i>x</i>Rh_<i>x</i>

Abstract

The orthorhombic CePd1−xRhx system exhibits a continuous evolution from ferromagnetic order in CePd (TC = 6.6 K) to an intermediate-valence ground state in CeRh. Here we report low-temperature (T≥0.08 K) specific-heat measurements for concentrations 0.80≤x≤0.95 close to the disappearance of magnetic order (∼0.87). In contrast to x = 0.8, still demonstrating a smeared phase transition signature at 0.27 K, non-Fermi-liquid behaviour is observed in the electronic specific-heat coefficient at x = 0.85. For higher Rh concentrations a weak power-law dependence with α≈0.4 is found. Upon applying magnetic fields Fermi-liquid-like behaviour ΔC(T)/T∼const is recovered in all the different samples. The magnetic entropy as well as the concentration of unscreened magnetic moments at 2 K indicate a broad distribution of local TK values ranging from well below 2 K to far above 50 K.