Electronic sputtering of Gd 3Ga 5O 12 and Y 3Fe 5O 12 garnets: Yield, stoichiometry and comparison to track formation

Abstract

The results of present paper have shown that sputtering of yttrium iron garnet (Y 3Fe 5O 12) under swift heavy ions in the electronic energy loss regime is non-stoichiometric. Here we are presenting additional experimental results for gadolinium gallium garnet (Gd 3Ga 5O 12) as target. The irradiations were performed with different ions ( 50Cr (589 MeV), 86Kr (195 MeV) and 181Ta (400 MeV)) impinging perpendicularly to the surface. As earlier, the sputtering yield was determined by collecting the emitted gadolinium and gallium atoms on a thin aluminium foil, placed upstream above the target and analyzing the Al catcher by Rutherford backscattering. Also for Gd 3Ga 5O 12, the emission of Gd and Ga is non-stoichiometric. Sputtering appears above a critical electronic stopping power of S th = 11.6 ± 1.5 keV/nm, which is larger than the threshold for track formation, in agreement with other amorphisable materials. In addition, the angular distribution of the sputtered species was measured for Y 3Fe 5O 12 and Gd 3Ga 5O 12 using 200 MeV Au ions impinging the surface at 20° relatively to the surface. For the two garnets the ratio of Y/Fe (and Gd/Ga) varies with the angle of emitted species and the stoichiometry seems to be preserved only for an emission perpendicular to the surface.