Magnetic Structures of Holmium. II. The Magnetization Process

Abstract

Neutron-diffraction measurements have been made on single-crystal holmium at temperatures ranging from 4.2 to 120°K in applied magnetic fields up to 22.3 kOe in order to study the magnetization process of this material. At low temperatures, the $b$ direction in the basal plane is an easy axis. For a field applied parallel to an $a$ direction, the moments are aligned parallel to the closest $b$ directions. At higher temperatures the effect of a field applied parallel to a $b$ direction is to transform the system to a $b$-axis ferromagnet after causing it to pass through one or two (depending upon the temperature) intermediate fanlike oscillatory structures. Similar oscillatory configurations are produced by the application of a field parallel to an $a$ direction. The $a$-axis ferromagnet is not produced in fields up to 22.3 kOe. A characterization of the four intermediate structures observed at 50°K was made and schematic phase diagrams in the $H-T$ plane were extracted from the diffraction and magnetization data. Studies of the remanent state at 4.2°K were made, and are reported.