Ultrathin Co films with Pt and Au covers—magnetic and structural properties driven by Ga⁺ ion irradiation

Abstract The X /Co 3 nm/ Y (where , = Au, Pt) trilayers with as deposited in-plane magnetization alignment were irradiated 30 keV Ga + ions in the wide range of ion fluence. samples investigated by means complementary techniques: magneto-optical magnetometry and spectroscopy (in photon energy from 1.2 eV to 4.5 eV), magnetic force microscopy, positron annihilation spectroscopy, x-ray diffraction reflectivity. Difference miscibility interface atoms is clearly manifested various intermixing extent at Co/Pt Co/Au interfaces consequently properties trilayers. Low irradiation fluence (∼10 14 cm −2 ) leads ∼1 nm broadening without visible surface etching for all samples, which related a distinct drop anisotropy. However, high (∼5 × 10 15 results enhanced significant nm) partially removing also Co atoms. Tensile strains (up 0.5%) developed cover layers. tensile strain, layers creation Co–Pt(Au) alloys different composition formed are correlated increase Moreover it was observed that substitution Au instead Pt (as cap or buffer layer) substantial perpendicular Maximal magnetooptical parameters Pt/Co/Pt layer. Irradiation induced changes concentration profiles revealed using spectra, reflectivity spectra simulations use binary collision approximation.