Magnetic field-dependent spin structures of nanocrystalline holmium.
The results are reported of magnetic field-dependent neutron diffraction experiments on polycrystalline inert-gas condensed holmium with a nanometre crystallite size (D = 33 nm). At T = 50 K, no evidence is found for the existence of helifan(3/2) or helifan(2) structures for the nanocrystalline sample, in contrast with results reported in the literature for the single crystal. Instead, when the applied field H is increased, the helix pattern transforms progressively, most likely into a fan structure. It is the component of H which acts on the basal-plane spins of a given nanocrystallite that drives the disappearance of the helix; for nanocrystalline Ho, this field is about 1.3 T, and it is related to a characteristic kink in the virgin magnetization curve. For a coarse-grained Ho sample, concomitant with the destruction of the helix phase, the emergence of an unusual angular anisotropy (streak pattern) and the appearance of novel spin structures are observed.
['Szary|Philipp|P|', 'Kaiser|Daniel|D|', 'Bick|Jens-Peter|JP|', 'Lott|Dieter|D|', 'Heinemann|André|A|', 'Dewhurst|Charles|C|', 'Birringer|Rainer|R|', 'Michels|Andreas|A|']
spin structures nanocrystalline holmium neutron diffraction magnetic materials rare earth metals