The easy magnetization directions in R6Fe23 intermetallic compounds: A crystal field analysis

X-ray diffraction patterns on magnetically aligned powder samples of R6Fe23 (R=Dy, Er, Ho, and Tm) show that these compounds all magnetize along a [111] easy direction. At first sight it is difficult to reconcile the common easy magnetization direction of Er6Fe23 and Tm6Fe23 on one hand, with Dy6Fe23 and Ho6Fe23 on the other, since the respective B20 rare earth crystal field parameters of these pairs of compounds are opposite in sign. In this article we show that the crystal field stabilization energy of the [111] direction, relative to either [100] or [110], varies as the square of the crystal field term B20, thereby providing an explanation for the common [111] direction of easy magnetization. copyright 1997 American Institute of Physics