By varying the Ga concentrations x of EuTm2Fe5-xGaxO12 from x = 0 to about 0.8, thin magnetic films supporting stable bubbles with diameters from 0.5 to about 8μm, respectively, are deposited epitaxially onto gadolinium gallium garnet substrates oriented (111). For low values of x, the Ga segregation coefficient is about 2 and it decreases slightly as x increases. Thus, films contain roughly twice as much Ga as the LPE fluxed melts in which they grow. Both the characteristic length and magnetic bubble stability factor (Q) increase rapidly with x and, to a lesser degree, so does the uniaxial anisotropy field HA while both 4πM and the uniaxial anisotropy Ku decrease. © 1975.