Magnetocrystalline anisotropy of Eu:YIG LPE films grown on (111) substrates

As previously reported, epitaxial films of Eu:YIG exhibit a strong dependence of the uniaxial anisotropy K/sub u/ upon Pb content. Magnetocrystalline and uniaxial anisotropies were derived simultaneously from an analysis of the FMR rotation spectra of (111) films about an in-plane (110) axis. The (111) EuIG films are grown on NdGaG, Eu2Y1IG films on SmGaG, and Eu1Y2IG and YIG films on GdGaG substrates by the LPE tipping process. The Pb contents range from 0.5 to 6 wt percent for growth temperatures ranging from 895 to 7400C. Bulk values are assumed or extrapolated for the magnetization. For EuIG, the room temperature value of K1 is --34,000 ergs/cm3 for zero Pb; this is decreased in magnitude by about 30 percent by a 6 wt percent Pb addition. Similar dramatic effects occur in the other members of the Eu:YIG system. In the case of YIG, the magnitude of K1 is almost doubled by a similar addition of Pb. These changes in K1 cannot be explained on the basis of a simple dilution model in which Pb displaces Eu or Y on the dodecahedral sites of the garnet. (auth)