Magnetic properties study of spin pinned NiFe/FeMn/NiFe heterogeneous multilayer films with different NiFe thicknesses

Abstract

FM (ferromagnetic)/AF (antiferromagnetic) heterogeneous multilayer films, with high-saturation magnetization (4πMs), low coercivity (Hc), and low ferromagnetic resonance (FMR) linewidth (∆H), have great application prospects in microwave/millimeter-wave devices. In this study, the Ni81Fe19 (t nm)/Fe50Mn50 (15 nm)/Ni81Fe19 (t nm) films were fabricated by DC magnetron sputtering, and the effects of thickness of the Ni81Fe19 on the microstructure, static magnetic properties and microwave properties were investigated. With the increasing thickness of Ni81Fe19 film, the saturation magnetization increased from 658 to 754 emu/m3. The in-plane and out-of-plane coercivity both decreased first and then increased, and ∆H decreased first and then raised from 193 to 95 Oe. When the thickness of the Ni–Fe film is 50 nm, the transition of the out-of-plane exchange bias field from the negative exchange bias to the positive exchange bias occurred. Remarkably, with a 50 nm Ni81Fe19 film, the multilayer films achieved excellent performance with high-saturation magnetization (4πMs, 722 emu/m3), low in-plane coercivity (Hc, 0.61 Oe), and low FMR linewidth (∆H, 95 Oe). The outstanding heterogeneous multilayer films exhibit great potentials in microwave/millimeter-wave devices.