Soft Magnetism and Morphology of Fe Films by Dual Ion Beam Sputtering

ABSTRACTFe films have been deposited by using dual ion beam sputtering apparatus under various conditions, and the dependence of their magnetic properties and morphology on preparation parameters such as film thickness, δt, and argon gas pressure, PAr, have been investigated in detail. The saturation magnetiza ion 4πMs of the specimen films did not change remarkably with 6t in the range of 50 ∼1000nm. However, with decrease of 6t below 50 nm, 4πMs decreased to less than 20 kG and coercivity Hc increased to more than 16 Oe. As PAr increased from 0.5 to 1.6 mTorr without ion bombardment, 4πMs decreased to less than 20 kG and Hc increased to about 20 Oe. The SEM micrographs of these films deposited at higher PAr showed the columnar structure. On the other hand, the films deposited at Yower PAr and ones bombarded by argon ions with proper kinetic energy during deposition did not present any texture and exhibited better soft magnetism. Such a morphology may be attributed to the difference in arrival energy of sputtered Fe particles to film surface and related closely to soft magnetism. It has been found that the dual ion beam sputtering method can control 4πMs and Hc with changing PAr and so prepare Fe films with superior soft magnetism by adjusting the kinetic energy of bombarding argon ions at lower PAr.