Effects of annealing and periodic ion bombardment on the soft magnetism of FexN films by a double ion beam sputtering system

Fe films with low nitrogen content have been prepared by using a dual ion beam sputtering apparatus. The effects of annealing at 300 °C for after-treatment of as-deposited films and the effects of periodic nitrogen ion bombardment onto growing Fe layers for growth process on their structure and magnetic properties have been investigated. The Hc of Fex N single layer films with nitrogen content of 2–3 at. % bombarded continuously by a mixture of argon and nitrogen ions decreased noticeably after annealing at 300 °C without significant decrease of saturation magnetization 4πMs. On the other hand , the Hc of the Fe/Fex N multilayered films bombarded periodically by the nitrogen ions at an accelerating voltage of 150 V decreased drastically, and took a minimum Hc of 1.5 Oe at proper cycle time tp. These results may be attributed to the relaxation of internal stress in films by annealing and the modification of microscopic morphology by ion bombarding, respectively.