Laser annealing of gallium-substituted garnet epitaxial films in pressurized oxygen

The effects of laser annealing Ga-substituted EuYIG epitaxial films in still, controlled ambients of air and one to five atmospheres of pure oxygen have been studied. An approximately logarithmic increase in saturation magnetization (
4\pi M_{s}
) and decrease in film magnetic Q factor were observed with increasing oxygen pressure in the annealing ambient. Compared with the most successful previous experiments, annealing at five atmospheres of oxygen displaced nearly twice the fraction of Ga from tetrahedral to octahedral lattice sites. As evidenced by the lack of film damage, the correlation of lattice parameter with the location of the Ga ions and the lack of broadening in the ferromagnetic resonance (FMR) lines, effective annealing temperatures above 1850K were achieved with no significant loss of oxygen from the films. The use of FMR to deduce the extent of film annealing was affirmed through the agreement of independent measurements of
4\piM_{s}
by bubble statics and SQUID magnetometry in films indicated to be homogeneous by FMR.