Magnetic and electronic properties of DyNi5-xAlx compounds

Abstract

The DyNi5-xAlx compounds crystallize in CaCu5-type structure for an aluminum content xless than or equal to1.5 and in HoNi2.6Ga2.4 type for xgreater than or equal to2. The saturation moments per formula unit extrapolated at 0 K, in composition range x<2 are similar to9.2 mu(B) in agreement with x-ray photoelectron spectroscopy studies which show negligible crystal field effects. For xgreater than or equal to2 a mictomagnetic type contribution to magnetic ordering develops which becomes dominant only for the DyNi2Al3 compound. Band structure calculations on DyNi5-xAlx show that the Dy 5d band is polarized parallel to the 4f moment. For DyNi5 the nickel moments at 2c and 3g sites are antiparallel oriented to that of Dy. The nickel contributions to magnetization decrease when increasing aluminum content and are near nil for xgreater than or equal to2. Above the Curie points the reciprocal susceptibilities follow linear dependencies. The effective nickel moments decrease from 2.11 mu(B)/atom (x=0) to 0.87 mu(B)/atom (x=2.5). The magnetic behavior of nickel is analyzed in models which take into account the electron correlation effects in d bands. (C) 2002 American Institute of Physics.