High-field magnetization process in Sm2Fe17N3.0: Importance of exchange-enhanced mixing of excited J multiplets

Abstract

The high field magnetization process in Sm2Fe17N3.0 has been investigated by using dc magnetic fields of up to 260 kOe generated by a hybrid magnet. It was found that the hard-axis magnetization at 4.2 K is only 78% of the easy-axis value in the field of 260 kOe, while at 296 K, it almost saturates at the same field, the saturation value being about 3% smaller than that along the easy axis. Experimental results have been analyzed on the basis of a model calculation taking the excited J multiplets of the Sm ion into account. It has been found that, when the field is applied along the hard axis at 296 K, the Sm magnetic moment rotates away from the field direction and finally, at the saturation field, it becomes antiparallel to the field so that the Sm and Fe moments are arranged ferrimagnetically. The origin of such a magnetization process was clearly explained as a result of the mixing of the excited J multiplets caused by the Sm–Fe exchange interaction. Observed anisotropy of saturation magnetization at 296 K was thus attributed primarily to this field-induced ferrimagnetic structure in the hard direction.