Epitaxial small magnetic bubble La-Sm-Lu iron garnet films grown on NdGaG substrates oriented (100) and (111)

Abstract

A Sm2.48Lu0.26(Pb,Pt)Fe5O12 garnet film composition grown earlier1 by LPE on NdGaG substrates oriented (100) and (111) is now diluted (in steps) to 56 mol% of a hypothetical La1.35Lu1.7Fe5O12 garnet. Most of the results reported are for films grown at 830 °C, but the effects of changing growth temperature for the compositions with the largest La-Lu substitutions are also discussed. La-Lu substitutions in fluxed melts significantly decrease film growth rates, and La must be present in melts in amounts in excess of those desired in the final crystal film. Both Pb from the fluxed melt and Pt from the crucible via the melt are incorporated into films in minor quantities. The ratio of rare earths and Pb to Fe and Pt in films is greater than the stoichiometric 0.6. The films support bubbles in the 0.5μm diameter range and have characteristic length l values of 0.037 to 0.062μm. Saturation magnetization values are 1700 to 2000 g (×10-4T). Domain wall damping coefficients are reduced in proportion to the amount of Sm replaced. The g factor is about 2 for all the films. The l, magnetic anisotropy Ku, and stability factor Q are decreased by La-Lu substitutions for (100) films, but they are first increased slightly then decreased for (111) films. With the largest La-Lu substitution, (100) films have zero Q. The highest l, Ku [3.6×105 erg/cm3 (×10 -1 J/m3)] and Q (2.5) exist for (100) films with no La.