Influence of working pressure on the structure and magnetic properties of polycrystalline iron films

Abstract

In this work, we aimed to evaluate the influence of working pressure on the structure and magnetic properties of the iron film. Iron films were deposited on Si (100) substrates by direct current (DC) magnetron sputtering at different working pressures. The X-ray diffraction (XRD) results indicated that all iron films were polycrystalline BCC structures with the obvious (110) orientation. When the working pressure increased, the (110) peak became weaker and wider, indicating that the crystallinity and the particle size decreased. Particle size gradually decreased, easily seen from the surface morphology. The (100) peak shifted toward the smaller angle with the increase of working pressure, displaying the production of compressive strain. The increase of the working pressure raised the density of defects, which was the origin of the strain. It was the main reason that the Hc dramatically increased. The atomic force microscope (AFM) results exhibited that low working pressure was conducive to obtaining uniform and smooth surface morphology. This is why the iron film at low working pressure can achieve better magnetic properties. The iron film deposited at 0.6 Pa had the largest saturation magnetization (Ms) and squareness ratio (Mr/Ms), the smallest coercivity (Hc), reaching 1573 emu/cm3, 0.86, 102 Oe, respectively.