Spatially resolved structure and domain wall propagation in defect induced SmCo/Co exchange spring magnet

Abstract SmCo5/Co exchange-coupled films with high saturation magnetization, and hence high energy product were fabricated on MgO substrates by sequential deposition of elemental Sm and Co layers at 450 °C followed by subsequent annealing at the same temperature for 1 h. Formation of defects induced multi-layered structures and the composition of individual layers were confirmed through high resolution Scanning Transmission Electron Microscopy (HRSTEM) imaging acquired on high angle annular dark field (HAADF) detector and Energy Dispersive X-ray (EDX) spectroscopy. Micromagnetic simulations and magnetic measurements further confirmed that the observed structure is coupled in rigid phase between soft and hard magnetic layers and the enhancement in coercivity results due to the domain wall pinning at the defects sites. This leads to the magnetic energy density in the film of the order of 22.2 MGOe which is close to the bulk value and have potential applications towards Micro-Electro-Mechanical Systems.