Sputtered high perpendicular magnetic anisotropy CoPt thin film on flexible substrate at low temperature

Abstract

In this study, CoPt alloy thin films with alternative sputtering of 0.4 nm-Co and 0.5 nm-Pt layers, [Co0.4/Pt0.5]n, on Pt underlayers were sputtered on rigid glass and soft PI (Polyimide) substrates at 100°C. The effects of repetition (n) of the [Co0.4/Pt0.5]n films on the magnetic properties and microstructures of [Co0.4/Pt0.5]n films were investigated. Results showed that [Co0.4/Pt0.5]4 film had a high perpendicular magnetic anisotropy (PMA (S⊥>0.98)) and a magnetocrystalline anisotropy constant (Ku∼1.12×107 erg/cm3), which were close to the properties of L11-CoPt film prepared at higher temperatures (∼300°C) as seen in previous works. Increasing repetition also increased residual stress and further reduced perpendicular magnetic properties. Thus, better magnetic properties would be obtained in the thinner case. The outstanding PMA properties of CoPt film still well kept as the rigid glass was replaced by flexible PI substrate. In this work, perpendicular magnetic CoPt film could be prepared at lower temperatures (∼100°C) on soft PI substrate. It strongly enhanced low temperature applications of hard magnetic alloy thin films, such as magnetic electronic components with high Ku and PMA on flexible substrate.