IMPROVEMENT OF FMR LINEWIDTH IN BISUBSTITUTED LUTETIUM IRON-GARNET THIN-FILMS FOR THE MSW-OPTICAL-MODE INTERACTION

Thin films of bismuth-substituted lutetium iron garnet (BiLuIG) for th e magnetostatic wave (MSW)-optical-mode interaction can be grown by li quid-phase epitaxy from the standard PbO-based melt system developed f or yttrium iron garnet (YIG). The addition of MgO to the melt to count eract the effect of lea on the ferromagnetic resonance (FMR) linewidth is investigated. BiLuIG thin films were grown on paramagnetic gadolin ium gallium garnet substrates with varying amounts of MgO added. The f erromagnetic resonance linewidth, optical waveguide absorption, and MS W passband were measured. The addition of magnesium reduced the FMR li newidth from an average of 3 Oe down to under 1 Oe, with little effect on other parameters.