Cryogenic magnetic properties of iron garnets diluted with Al-In and Ca-V-In combinations

Investigations of magnetic dilution in Y3Fe5O12 (YIG) indicate that magneti c and dielectric parameters suitable for microwave applications can be obta ined at cryogenic temperatures. For simultaneous dilutions of 35% into the octahedral (a) sublattice and 27% into the tetrahedral (d) sublattice, ther e were no apparent degrading effects on the dielectric loss tangents. At lo w temperatures, a-site substitutions of In caused the expected large increa ses in saturation magnetization and corresponding decreases in Curie temper atures. Moreover, measurements of hysteresis loops showed that coercive fie lds similar to0.5 Oe could be obtained at T < 77 K despite the likely sharp rise in anisotropy. Dilution by In also lowered anisotropy fields by a fac tor greater than five from that Of Y-3(Fe,AI)(5)O-12 in both {Y,Ca}(3)(Fe,V In)(5)O-12 and Y-3(Fe,Al,In)(5)O-12 compounds.