Magnetic properties of highly diluted PdFx, and PtFex-alloys .1. Magnetization at Kelvin temperatures

Localized 3 d magnetic moments polarize in palladium and platinum matrices the Pd 4 d and Pt 5 d conduction electrons in their neighbourhood. This leads to effective ''giant magnetic moments'' In,, We have measured the magnetization M(x,B,T) of each nine PdFex and PtFex samples with 2 ppm less than or equal to x less than or equal to 260 ppm at 1.6 less than or equal to T less than or equal to 300 K and 0 less than or equal to B less than or equal to 6.0 T. Our main motivation is to determine the size of the giant magnetic moments induced by highly diluted Fe impurities in both transition metals. From the data, taken in a wide polarization range, 9% less than or equal to M/M(sat) less than or equal to 93%, we determine the impurity concentrations x, the effective moments mu(gm) and the spin quantum number J of the samples by fitting to the Brillouin function. For PdFex, we find a slight increase of mu(gm) with concentration from (13 +/- 1.5) mu(B), at x = (2.5 +/- 0.5) ppm to (16 +/- 1) mu(gm), at x = (220 +/- 30) ppm. For PtFex, the moments are almost constant with mu(gm), = (7.8 +/- 1) mu(B) at x = 2 to 14 ppm and mu(gm) = (8.6 +/- 0.7) mu(B) at x = 75 to 95 ppm. For all samples we obtain a concentration independent very large or possibly infinite spin quantum number, J greater than or equal to 100, which means that the localized giant moments behave as classical ones at T > 1.6 K and Tesla magnetic fields.