Dissociation of spin objects in geometrically frustrated CdFe ₂O₄

Using inelastic neutron scattering, we measured the diffuse scattering pattern of the geometrically frustrated ¹¹⁰CdFe₂O ₄. The observed pattern resembles that of ZnCr₂O ₄, indicative of strong nearest-neighbor antiferromagnetic correlations in contrast to the ferromagnetic nearest neighbor interactions of the isomorphic ZnFe₂O₄. This result demonstrates that the subtle 90° Fe³⁺-O-Fe³⁺ interaction changes its nature by chemical pressure. Meanwhile, the temperature dependence of the diffuse scattering shows hexagonal spin objects decay very gradually with increasing temperature and can be seen even at temperature as high as five times Curie-Weiss temperature. At low temperatures, spin freezing with only short-range correlations is observed associated with 13 K susceptibility anomaly. No long-range order is found down to 0.1 K with applied field of up to 9 T.