On the nickel magnetic behaviour in rare-earths compounds

The x-ray photoelectron spectroscopy (XPS) study, magnetic measurements and band structure calculations were performed on RNi₂, RNi₃, RNi₅ and R₂Ni₁₇ compounds, where R is a rare-earth or yttrium. The presence of small nickel moments was shown in almost all compounds with magnetic rare-earths. The nickel moments are dependent on the site location, their local environment, respectively. The R5d bands are negatively polarized, their values M_5d, being determined by additive contributions resulting from local 4f-5d and short-range 5d-3d interactions. The R5d band polarizations mediate the exchange interactions within the spatial extension of the unit cell. The Curie temperatures for a given series are linearly dependent on M_5d values with the same rate for both heavy and light rare-earth compounds. (paper)