Point-contact study of UCu4+<i>x</i>AI8–<i>x</i> compounds
Abstract
The first IVC derivative dV/dI(V) and its temperature dependence are measured for heterojunctions formed by UCu4+xAl8–x (x=0, 0.5, and 1.5) and pure metals Cu, Fe and Ni. It is found that the main peculiarities of the dV/dI(V) dependence take place at a temperature below T* which is close to the Néel temperature for compounds with x=0 and 0.5. The behavior of dV/dI(V) in the case is in good agreement with the dependence calculated by using the thermal model of current flow through a point contact, taking into account the degradation of the properties of the material near the surface. It was found that T* for the sample with x= 1.5 considerably exceeds the temperature at which a resistivity peak is formed due to coherent effects during a transition to the heavy-fermion state.