MAGNETOCRYSTALLINE ANISOTROPY OF NON-UNIAXIAL R-T MAGNETIC-MATERIALS STUDIED BY THE SINGULAR POINT DETECTION TECHNIQUE - AN APPLICATION TO R(2)FE(17-X)GA(X) COMPOUNDS (R=Y OR GD AND X=0 OR 1)

The easy magnetization direction of R(2)Fe(17-x)Ga(x) lies within the basal plane over all magnetic ordering temperatures. A spinning-sample magnetic alignment technique was used to align the basal planes of fi ne single crystallites of R(2)Fe(17-x)Ga(x) (R = Y or Gd and x = 0 or 1) to be parallel to each other. The degree of magnetic alignment was checked by x-ray diffraction. The magnetocrystalline anisotropy field of R(2)Fe(17-x)Ga(x) has been determined by a singularity appearing in the curve of d(2)M/dt(2) versus H measured on a magnetically aligned sample when an external field is applied perpendicular to aligned basa l planes. The temperature dependence of the anisotropy fields was meas ured from 4.2 K up to the corresponding Curie temperatures. It was fou nd that the Curie temperatures of R(2)Fe(17) compounds with R = Y or G d were enhanced upon partial substitution of Fe by Ga. However, the ma gnetic anisotropy fields of Ga-containing compounds are smaller than t hose of the corresponding pure R(2)Fe(17) compounds at low temperature s.