Nitrogen ion implantation effect on the magnetic properties of garnet films

By using a commercial implanter with 200 kV acceleration potential, the effect of nitrogen ion implantation at different energy and dosage has been examined. The results of magnetostatic measurement show that nitrogen ion implantation can also suppress hard bubbles with the same results as Ne and He ion implantation. The lattice damage induced by the implantation has been investigated by x-ray double crystal diffraction technique. The rocking curves show that at same energy, the lattice strain increases with increasing dosage and then tends to saturation. The saturation value of maximum strains are as high as 1.9% and 1.8% for 75 keV and 100 KeV N ion energy. At same dosage the lattice strain decreases with increasing energy. After annealing the sample at temperatures from 300°C to 900°C in air for half hour the maximum strain decreases linearly with increasing annealing temperature. After 350°C annealing the lattice strain decreases by one third of as-implanted sample. At high dosage implantation of 170 KeV 3 × 10¹⁵N+/cm²it was found that hard bubble can still be suppressed. But due to overdamage an amorphous layer was formed. On the x-ray diffraction curve no obvious diffraction subpeaks corresponding to implanted layer were observed. The effect of high temperature annealing on the overdamaged layer was examined The multiple implantations of nitrogen and helium ions for contiguous disk bubble devices were done. The bias margin of 17 Oe at drive field of 45 Oe was obtained for propagation tracks with 12 um period in 3 um bubble films.