Bubble properties of garnet films prepared from molybdate fluxes

Abstract

Magnetic bubble garnet films have been prepared from a flux composed of lithium and rare earth molybdates using liquid phase epitaxial techniques. In general, the quality and magnetic properties of 〈111〉 films prepared on GGG substrates compare favorably with the properties of similar garnets prepared from PbO based fluxes. A notable exception, however, is a persistent, unusually low value of the growth induced anisotropy (K_u). Typically, Y_3−xEu_xFe_5−yGa_yO₁₂ films grown at ∼950 °C containing as much as Eu=0.6 and Ga=0.9 have a moment (4πM_s) ?400 G and K_u?10³ ergs/cm³ when grown from the molybdate flux. Films prepared on 〈100〉 substrates exhibit comparably low K_u values and K₁ values of ∼−2.3×10³ ergs/cm³. As these films are virtually contaminant free with regard to the flux components, and PbO and B₂O₃ additions have essentially no effect on K_u, our present understanding of the nonrandom rare earth ion distribution responsible for growth induced anisotropy in garnets may not be adequate to explain these data. Other anomalies which have been observed in these films and will be discussed are the occurrence of triangular bubble domains and square lattice bubble arrays.