Magnetization Reversal and Domain Structures in Perpendicular Synthetic Antiferromagnets Prepared on Rigid and Flexible Substrates

Ferromagnetic (FM) layers separated by nonmagnetic metallic spacer layers can exhibit Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling, which may lead to a stable synthetic antiferromagnetic (SAF) phase. In this article, we have studied magnetization reversal by varying the number of bilayer stacks [Pt/Co] as well as thicknesses of Ir space layer tIr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{Ir}$$\end{document} on rigid Si(100) and flexible polyimide substrates. The samples with tIr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{Ir}$$\end{document} = 1.0 nm show a FM coupling, whereas samples with tIr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{Ir}$$\end{document} = 1.5 nm show an antiferromagnetic (AFM) coupling between the FM layers. At tIr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{Ir}$$\end{document} = 2.0 nm, it shows a bow-tie shaped hysteresis loop indicating a canting of magnetization at the reversal. Higher anisotropy energy compared to the interlayer exchange coupling (IEC) energy is an indication of the smaller relative angle between the magnetization of lower and upper FM layers. We have also demonstrated the strain-induced modification of IEC as well as magnetization reversal phenomena. The IEC shows a slight decrease upon application of compressive strain and increase upon application of tensile strain, which indicates the potential of SAFs in flexible spintronics.