Liu Gang

1 GeV Ar ions induced amorphization in garnet

Abstract Amorphization phenomenon of yttrium iron garnet (YIG) Y 3 Fe 5 O 12 induced by 1 GeV Ar ions irradiation at the temperature 195 K has been investigated by means of the sample-tilting X-ray diffraction (STD), optical absorption spectroscopy, Mossbauer spectroscopy and saturation magnetization measurement. The analysis results indicate that there exist a critical dose 1.0 × 10 14 ions/cm 2 and a threshold value of electronic energy loss S e = 2.9MeV/μm. Above both values the lattice constant a , the optical absorption coefficient α, and the fraction of the paramagnetic phase F p increase with the increase of electronic energy loss, but saturation magnetization decreases. For the first time, the nearly complete amorphous state was observed at S e = 8.3MeV μm with irradiation doses equal or more than 1.0 × 10 14 ions/cm 2 . It is found that the transformation from crystalline to amorphous state is a gradual process in which the electronic stopping power plays a main role and a certain dose is needed.