Magnetic Properties of Evaporated Ni Thin Films: Effect of Substrates, Thickness, and Cu Underlayer

摘要

Ni thin films have been deposited by thermal evaporation onto glass, Si, Cu, mica, and Al2O3 substrates with and without a Cu underlayer. The Ni thicknesses, t, are in the 4 to 163 nm range. The Cu underlayer has also been evaporated with a Cu thickness equal to 27, 52, and 90 nm. The effects of substrate, Ni thickness, and the Cu underlayer on the magnetic properties of Ni are investigated. Magnetic properties were inferred from the vibrating sample magnetometer (VSM) set-up. The substrates induce not only different coercive field H (C) values but also the origins of the H (C) values are different. The squareness S depends on substrate and t and seems to be relatively large in Ni/glass and Ni/Cu, and small in Ni/Si and Ni/mica. The Cu underlayer leads to an overall increase of H (C) and the saturation H (sat) and to a decrease in the remnant magnetization; the increase in H (sat) may be related to a stress-induced anisotropy in Ni/Cu/substrates.