Molecular engineering in the design of microwave ferrimagnetic garnets

Recent advances in the study of microwave ferrites and garnets have resulted in a better understanding of the relationship between magnetic properties and the fundamental crystal structure. This article presents a review of the way in which the crystal structure of microwave garnets may be designed in order to realize the many different combinations of magnetic properties required by the designer of non-reciprocal microwave ferrites. The discussion relates to rare-earth and yttrium-containing garnets of the form Y 3-α R α Fe 5 O 12 (R = rare earth Sm-Lu) and considers the effect of substitutions of Al, Ga, In, Mn, Ce, Ca and V on magnetization, gyromagnetic resonance, magnetic loss, high-power instability threshold and magnetostriction effects.