The magnetic modification of exchange bias materials by ‘ion bombardment induced magnetic

patterning’ has been established more than a decade ago. To understand these experimental

findings several theoretical models were introduced. Few investigations, however, did focus on

magnetic property modifications caused by effects of ion bombardment in the ferromagnetic

layer. In the present study, the structural changes occurring under ion bombardment were

investigated by Monte-Carlo simulations and in experiments. A strong reduction of the

saturation magnetization scaling linearly with increasing ion doses is observed and our

findings suggest that it is correlated to the swelling of the layer material based on helium

implantation and vacancy creation.