Magnetic transition in (formula presented) single crystals probed by neutron scattering in magnetic fields

Single-crystal neutron diffraction was employed to study the magnetic transition in the pseudobinary Laves-phase compounds (formula presented) under external magnetic fields up to 4 T. The magnetic scattering amplitudes measured for the reflections to which either the localized (formula presented) Co moment solely contributes, give direct evidence that the onset of long-range magnetic order for both magnetic sublattices occurs at about the same temperature (formula presented) and 0.4, respectively. The magnetic-susceptibility and specific-heat data, obtained on the same specimens, were also measured. In agreement with the neutron-diffraction data the macroscopic measurements showed no multiple phase transitions as opposed to earlier measurements on powder samples, which are presented and discussed as well.