Development of High Energy Thin Layers of Exchange Spring Magnets Originating from Rare Earth Magnets of NdFeB/FeCo

In this study, nine Nd-Fe-B and FeCe thin films with 10-50 nanometers width were prepared by RF magnetron sputtering on the Si/SiO2 substrate. Then, the films were annealed at 800 oC for 5 sec in rapid thermal annealing furnace. X-ray diffractometry (XRD) was used to analyze the phase composition of layers and existance of Nd2F14 and Fe65Co35 phase was confirmed, without formation of any other secondary phase. The layers surfaces were investigated using Field Emission Scanning Electron Microscope (FESEM). The morphology of layers surfaces was investigated using Atomic Force Microscope (AFM). The magnetic properties of layers were evaluated by vibrating sample magnetometer with maximum applied field of 24kOe, in order to measure coercivity, saturation of magnetization, hysteresis area, rectangular ratio and (BH)max. It was found that all layers have vertical magnetic anisotropy. Increasing thickness of FeCo resulted in increasing saturation of magnetization, coercivity and saturation magnetization. The results indicate that by an increase in thickness of FeCo up to 20nm, exchange interaction strength between hard and soft magnetic layers is enhanced and, consequently, maximum energy induced from this hetero-structure is increased.