Effect of post-annealing temperature on the microstructure and magnetic properties of Ce:YIG thin films deposited on Si substrates

摘要

Amorphous Ce_1Y_2Fe_5O_(12) (Ce:YIG) thin films deposited on single crystal Si(100) and thermally oxidized Si(100) substrates by pulsed laser deposition were annealed in the temperature range of 700-1000℃ in air. The annealing temperature dependence of microstructure and magnetic properties of Ce:YIG films was studied using X-ray diffraction combined with vibrating sample magnetometer. The results show that single phase of polycrystalline Ce:YIG thin films can be obtained by the post-annealing of as-deposited films at the temperature of 700℃. However, two steps of phase segregation of Ce: YIG occur as the post-annealing temperature increases: at first, Ce: YIG is decomposed into YIG and non-magnetic CeO_2 when annealed at 800℃; then YIG continues to be decomposed forming Fe_2O_3 when the temperature is increased up to 900℃. Consequently, the saturation magnetization of Ce:YIG films decreases first and then increases with the post-annealing temperature going up, which indicates that the saturation magnetization of Ce:YIG films is mainly related to the phase composition of the films. Meanwhile, the presence of SiO_2 buffer layer can significantly enhance the saturation magnetization of Ce:YIG films.