Radiation induced mobility changes in bubble-domain materials

Domain wall mobility changes have been observed in magnetic bubble domain materials (rare-earth iron garnet films) following irradiation with 3 MeV protons to fluences of 5 &time; 10 16 p/cm 2 and 10 17 p/cm 2 . The mobility was observed to decrease by 24% and 43%, respectively. No measurable changes in the coercive field have been observed. Similar experiments with 1 MeV electrons to 10 16 e/cw 2 and 14 MeV neutrons to 10 14 n/cm 3 have yielded negative results. A damage threshold of ∼ 10 16 p.cm 2 at 3 MeV is established and a fast neutron damage threshold is inferred to be ∼ 10 18 n/cm 2 . A slight broadening of the ferromagnetic resonance linewidth following the proton irradiations is evidence of increased magnetic damping caused by displacement damage in the garnet films.