Magnetic and Crystallographic Study of Neodymium-Substituted Yttrium and Gadolinium Iron Garnets

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Abstract
A study of the garnet systems {R5−xNdx}Fe2Fe3O12, R≡Y or Gd, indicates, as expected, that the moment contributed by the Nd3+ ion adds to that of the resultant contributed by the iron sublattices, similar to the results of earlier work by others on intermetallic systems involving rare earths and also on Nd- and Pr-substituted yttrium iron garnets. This has been explained on the basis that in the L−S ions Nd and Pr, J is generally directed oppositely to S. It has been found that the anisotropy introduced by the Nd3+ ion prevents saturation at applied fields up to 14 000 oe, and at first a null method involving the garnet system {Gd2−xYxNd}Fe2Fe3O12 was used to find the moment contributed by the Nd3+ ion at 0°K; the moment obtained by this method is 1.2 μB. Subsequently, measurements made to fields of 80 000 oe at 4.2°K on the garnets {Y2Nd}Fe2 Fe3 O12 and {Gd2Nd} Fe2 Fe3 O12 proved that the extrapolation of nB vs 1Ha to 1Ha=0 from the lower field values did not give the proper moments for these compounds. The specimens appeared to be saturated at fields above 70 000 and 60 000 oe, respectively, and gave moments of 6.2 μB and 7.7 μB, respectively, per formula unit. These values indicate moments for the Nd3+ ion of 1.2 μB and 1.3