Ferromagnetic resonance of chromium chalcogenide ferro-spinels

The magnetostriction constant λ111and λ100, the magnetocrystalline anisotropy constant K1, and the resonance linewidths ΔH111and ΔH100of CdCr2Se4and CdCr2S4have been measured by the ferromagnetic resonance technique at 9.5 GHz at 4.2 K. The crystals were grown by closed-tube vapor transport using CrCl3, and the samples for the measurements were subjected to different heat treatments after being shaped into spheres. The values of K, λ, and ΔH were found to depend strongly on the thermal history of the crystals; the presence of Cr²⁺always increased the absolute values of K, λ, and ΔH. The contribution of the dipole interactions between the Cr³⁺ions to the magnetostriction constants were calculated and found to be an order of magnitude greater than the very small values measured for the selenium-annealed crystals.