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; 10¹⁶ p/cm² and 10¹⁷ p/cm². 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 10¹⁶ e/cw² and 14 MeV neutrons to 10¹⁴ n/cm³ have yielded negative results. A damage threshold of ∼ 10¹⁶ p.cm² at 3 MeV is established and a fast neutron damage threshold is inferred to be ∼ 10¹⁸ n/cm². 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.