Interface mixing and magnetism in Ni/Si bilayers irradiated with swift and low-energy heavy ions

We report on heavy-ion-induced modifications of 65–75 nm thick Ni/Si bilayers in the regime of electronic stopping (350 MeV 197Au26+-ions) and nuclear stopping (400 keV Xe+-ions). The samples were analyzed by means of Rutherford back-scattering spectroscopy, X-ray diffraction and magneto-optical Kerr effect. For both types of ions, interface mixing was observed, correlated with full relaxation of the as-deposited stress and uniaxial magnetic anisotropy. For the higher fluences, full intermixing, rebuild-up of stress and loss in magnetic texture occurred. It can be concluded that for both types of ion beam stopping, interface mixing and changes of magnetization occur for similar reasons.