Magnetic and electronic properties of the LaNi5-xCux system

The magnetic properties of the LaNi5-xCux system (x≤1.5) were investigated in the temperature range 1.7-300 K. The magnetic susceptibilities χ increase up to a characteristic temperature Tmax and then decrease. At T ≤ 10 K the χ-values of LaNi5 follow a T2-dependence. At temperatures above a characteristic temperature T* a Curie-Weiss-type behaviour was observed for all samples investigated. The effective nickel moments decrease when increasing the Cu content. X-ray photoelectron spectroscopy measurements and a band-structure calculation show that the Fermi level is shifted towards a region with lower density of states when Cu is substituted for Ni. There is a weak hybridization between Ni and Cu d states. The magnetic properties were analysed in the spin-fluctuation model. The smaller values of the effective moments of nickel as compared to the free Ni2+ ion indicate that LaNi5-xCux is a non-saturated spin-fluctuation system. (author)