SPIN REORIENTATION IN TB1-XYXFE11TI COMPOUNDS

The Tb1-xYxFe11Ti (x = 0, 0.2, 0,4, 0.6 and 0.8) compounds have been s tudied in magnetization and ac-susceptibility measurements as a functi on of temperature. The results show that the Tb1-xYxFe11Ti compounds w ith x = 0, 0.2 and 0.4 undergo a spin reorientation of the axis-to-pla ne type (referred to decreasing temperature), while the samples with x = 0.6 and 0.8 remain easy-axis compounds down to the lowest temperatu re measured (4.2 K). The spin-reorientation temperature, T(sr), is fou nd to decrease with increasing Y content. The observed temperature dep endence of the magnetic structure of this series of compounds has been analyzed on the basis of a crystal-field model with the following set of crystal-field parameters: B-2(0) = 0.45 K, B-4(0) = -1.8x10(-4) K and B-6(0) = 0 K.