Study of magnetization reversal in ultrathin magnetic multilayers using in situ MOKE

Abstract

Effects of laminated soft layer on magnetization reversal of exchange coupled composite mediaThe magnetization reversal mechanism in Co/Pt and CoCrTa/Pt thin film multilayers was investigated in situ using a magneto-optical Kerr effect ͑MOKE͒ apparatus. Multilayers Nx(Co/Pt) and Nx(CoCrTa/Pt) with different amounts of doped Cr 17 Ta 5 were sputtered in high vacuum. The growth was interrupted at intervals of two bilayers to perform perpendicular MOKE loops in the range from N ϭ 2 to N ϭ 20. The Draaisma and de Jonge model was adapted to analyze the hysteresis loops with the domain wall energy density as a fitting parameter. The broad consistence of the experimental data and theory shows that the incorporation of Cr and Ta in the magnetic layer lowers the domain wall energy density. The model successfully predicts the thickness dependence of the loop squareness, which decreases with increasing N. According to the model, the domain repetition length d is in the range of 900-2100 Å, and the domain wall energy density w is in the range of 1.68-11.1 erg/cm 2 .