Magnetic structure of ternary rare-earth alloy Ho1/3Tb1/3Er1/3

Temperature dependent neutron powder diffraction measurements have been performed on the ternary rare-earth alloy Ho1/3Tb1/3Er1/3. A dominant hexagonal closed packed structure is found, with a surface impurity phase that does not have any discernible magnetic signal. Three different magnetic phase transitions have been identified in the sample: (1) paramagnetic to helical k = (0,0,0.18) near T1 = 90 K, (2) addition of another helix k = (0,0,0.34) near T2 = 70 K, and (3) onset of ferromagnetism near T3 = 45 K. There is a degree of ambiguity in the direction of the ferromagnetic moments, but we argue that a c-axis ferromagnetic moment is most plausible. At T = 3.5 K the magnetic moments are found to be mc = 2.83 μB, mab[kc = 0.19] = 3.96 μB, and mab[kc = 0.37] = 3.17 μB.