Effect of swift heavy ion irradiation on sputter deposited SiO2/Co/Pt/SiO2 multilayers

The present paper reports the structural and magnetic properties of sputter deposited (SiO2/Co/Pt/SiO2)n multilayers deposited by magnetron sputtering on quartz substrates as a function of the number of layers (n = 1, 2, 3, 4) and the effect of swift heavy ions (120 MeV Ag9+) irradiation on them. The deposition of multilayers was performed under high vacuum on substrates held at 780 °C. All the deposited films were found to contain stoichiometric (Co50Pt50) particles with L10 ordered structure and their coercivity increases with the increasing number of layers. The formation of L10 ordered structure was evident by the presence of (0 0 1), (1 1 0) super lattice peaks in XRD patterns and from selected area electron diffraction pattern images in TEM. The coercivity of these films was measured using SQUID magnetometer. Irradiation of these films induced an increase in coercivity together with a loss of chemical ordering in the metal phase. However, the easy axis of magnetization remained in the film plane contrary to the case of FePt particles in silica matrix as previously reported.

► Effect of swift heavy ion irradiation on Co/Pt multilayer has been studied.
► Structural and magnetic properties are found to vary with number of layers.
► Coercivity has been found to increase with increase in number of layers.
► X-ray diffraction (XRD) and Transmission electron microscopy (TEM) results confirm the L10 structure of CoPt particles.
► Particle size reduces and coercivity increases after irradiation.