Spin reorientation processes in hard magnetic pseudoternaries (Er/sub x/Nd/sub 1-//sub x/)2Fe14B

The effect of the different kinds of anisotropies (axial, conical, and planar) competing in the same compound with different grades of influence with the concentration, x, produces a wide range of peculiar behaviors. We have studied the magnetic anisotropy in this series by means of the thermal evolution of the spin reorientation transition (SRT) with concentration. We have measured the ac initial magnetic susceptibility for the concentrations x = 0, 0.2, 0.4, 0.6, 0.8, 0.9, and 1. The results clearly show peaklike anomalies which allow us to obtain the critical temperature for the phase transition. We have also measured the magnetization parallel and perpendicular to the applied magnetic field on magnetically aligned powder samples in order to determine the thermal evolution of the orientation of the easy magnetization direction. The compounds with intermediate concentrations (0.2≤x≤0.8) present two peaklike anomalies in the range of temperature measured (3.5--350 K), which have been associated with critical phenomena related to the SRT (axial→cone 1 and cone 1→cone 2). The remaining concentrations display SRT axial→planar in the case of Er-rich compounds and axial→cone in the Nd-rich ones