Magnetization and 55Mn Hyperfine Field in RMn2 (R = Rare Earth) Intermetallic Compounds
The RMn2 (R = rare earth) compounds show some interesting crystallographic features. The compounds with R = Gd, Tb and Dy have the cubic Laves phase (C15 type) structure (1), those with Nd (2), Er, Tm (3) and Lu crystallize in hexagonal Laves phase (C14 type) structure, while PrMn2 has β-Mn type structure (4). The compounds SmMn2 (5) and HoMn2 (6) occur in either the C14 or C15 type structure. The compounds for R = La, Ce, Eu and Yb are not known to exist. As noted earlier (3,7), the change in lattice parameter over the RMn2 series is more rapid than that in the corresponding Fe, Co and Ni series. This may be taken to imply that the Mn valence (and hence its magnetic moment) changes across the series. We have carried out magnetization studies on GdMn2, DyMn2 and HoMn2 and 55Mn hyperfine field measurements on several RMn2 compounds to obtain information about the Mn ion moment. We find that the Mn moment is non-zero in cubic Laves phase RMn2 compounds, decreases in going from GdMn2 to DyMn2 and becomes zero or nearly so in cubic HoMn2 as well as in hexagonal Laves phase compounds.
KeywordsArgon Hexagonal Olated GdMn
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