Magnetic Properties of Tb–Ho Single-Crystal Alloys. II. Neutron Diffraction Studies

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Abstract
A neutron diffraction study of single‐crystal Tb–Ho alloys is reported. Three single‐crystal samples, containing 10%, 50%, and 90% Ho, were studied in detail from 5–298°K. We find that all three alloys have similar ordered phases with uniform magnetic structures. Between the Néel temperature and Curie temperature, each alloy exhibits a spiral magnetic structure with the magnetic moments confined to the basal plane of the hcp structure. The temperature dependence of the interplanar turn angle changes gradually from that similar to pure Tb to that of pure Ho as the Ho concentration increases. Below the Curie temperature, all the alloys exhibit a collinearly ferromagnetic structure with the magnetic moments parallel to or closely parallel to the basal plane. The transition temperatures agree well with the corresponding values determined from magnetization measurements. The observed magnetic form factors also show a gradual change in shape as the Ho concentration increases from the shape similar to pure Tb to that of pure Ho. They show little change with temperature (within the accuracy of the present experiment) in the temperature range of the magnetically ordered states for each alloy. Similarities found between the magnetic properties of the 50% alloy and pure Dy are discussed.