First-order magnetization process in Nd2(Fe1−xAlx)17 single crystals

High field magnetization measurements have been performed for single crystals of Nd 2 (Fe 1− x Al x ) 17 . In the sample with x = 0.04, the easy direction is not within the c -plane at 4.2 K but in the plane spanned by the b - and c -axes. When the field is applied along the c -axis at 4.2 K, abrupt increases in magnetization have been observed successively at 115 and 150 kOe. These results have been well reproduced by a simple model calculation on the basis of the crystalline electric field theory.