The mechanism of phase formation in Pt/Co bilayers during ion beam mixing

• We propose a mechanism of phase formation in Pt/Co bilayers during ion beam mixing.
• We examine the influence of heat of formation during ion beam mixing in Pt/Co bilayers.
• Parameters deciding phase synthesis during ion mixing in Pt/Co bilayers are explored.

Ion beam mixing of Pt/Co/Si (Substrate) bilayers were carried out with a 4 MeV Si+ ion beam at two different temperatures – room temperature and 300 °C. When the mixing is carried out at 300 °C, diffusion of Co atoms to the top Pt layer is observed thereby synthesizing CoPt and Co3Pt crystalline phases. When the irradiation is carried out at room temperature, Co and Pt atoms diffuse inwards to the silicon substrate and no new crystalline phase formation is observed. We propose that the direction of movement of the atoms and the resulting concentration profile in the Pt/Co/Si bilayers during ion beam mixing decides the nature of phase synthesized.