Paramagnetic Resonance ofFe3+in Yttrium Aluminum, Lutetium Aluminum, and Lutetium Gallium Garnets

Abstract

The spin-Hamiltonian parameters have been determined for the ${\mathrm{Fe}}^{3+}$ ion when present as substitutional impurity in the series of isomorphous diamagnetic garnets. Most of the parameters vary rather slowly from host to host. It is shown that the dependence of the cubic field splitting in the octahedral sites on lattice parameters as obtained from the present results is consistent with the dependence of the same parameters on hydrostatic pressure for substitutional ${\mathrm{Fe}}^{3+}$ in MgO. The fourth-order axial-field parameter $F$ does show appreciable variation among the various hosts; this is discussed in terms of the extrapolation to yttrium iron garnet, and the calculation of the crystal-field-induced magnetic anisotropy in the latter.