Magnetic properties of RCo5-based systems

Band structure calculations and magnetic measurements were performed on (GdxY1−x)Co4Si as well as on YCo4M compounds, where M = Ga, Al, and Co. The substitutions both at rare-earth and cobalt sites influence strongly the cobalt moments as well as the Curie temperatures. When Y is replaced by Gd, in GdxY1−xCo4Si system, the mean cobalt moments increase from 0.73μB/atom to 1.25μB/atom. The computed magnetic moments per formula unit agree rather well with experimental data. The reciprocal susceptibilities for ferrimagnetic compounds show non-linear temperature dependences. The effective cobalt moments are little dependent on composition. The ratio r   between the mean number of cobalt spins determined from effective and saturation cobalt moments, respectively follows a dependence on Curie temperature of the form r∝Tc−2/3. The magnetic behaviour of cobalt is analysed in spin fluctuations model.

► The GdxY1-xCo4Si compounds with x ≥ 0.2 are ferrimagnetic.
► The saturation Co moments are linearly dependent on exchange field.
► A linear relation of exchange splittings ΔE and Co moments was shown.
► The effective cobalt moments are little influenced by composition.