Neutron-Diffraction Studies of Magnetic Structures in Ho-Er Alloys

Abstract

Neutron‐diffraction studies were made on a single crystal of Ho_0.5Er_0.5 as well as on two polycrystalline samples, Ho_0.7Er_0.3 and Ho_0.4Er_0.6. The magnetic structures of these alloys at 4°K are ferromagnetic cone spirals propagating along the c axis, as in both end members. The magnitude of observed magnetic moments indicates that these alloys form uniform magnetic structures with respect to the cone angle. This conclusion is in contrast to the model in which the magnetic‐moment direction of each constituent atom is mainly determined by its own anisotropy with an average cone angle and spiral periodicity. The temperature dependence of magnetic intensities of the Ho_0.5Er_0.5 crystal has been studied in detail. The cone angle of the ferromagnetic cone structure increases with temperature and the structure transforms to a pure spiral mode at 33°K without a noticeable discontinuity in the total moment value. The spiral structure is retained up to the Néel temperature at 104°K in contrast to pure Er where an additional sinusoidally modulated phase was observed below the Néel point.