Magnetostatic mode suppression in layered yttrium iron garnet films

Preliminary results of experiments on the use of single-crystal Ca:YIG films to suppress selected MS modes in the output spectra of YIG-film microwave devices are reported. Two different two-layer structures are grown by LPE on GGG substrates: in one structure, a 13-micron-thick YIG layer is covered with a 4-micron-thick layer of Ca(0.15):YIG; in the other, a 4-micron-thick Ca(0.36):YIG layer is covered with a 12-micron-thick YIG layer. MS spectra of 2 x 2.8-mm and 3.8 x 2.8-mm chips of the respective two-layer films are presented and characterized. In the first structure, the MS surface-wave modes below the bulk (1, 1) mode are totally suppressed by the broad Ca:YIG background while the backward-volume modes are unaffected; in the second, backward-volume modes are suppressed, forward-volume modes are reduced, and surface modes are unperturbed. A three-layer structure suppressing all but the bulk mode (for filter or resonator applications) is proposed.