Study of the Switching Field Distribution and the S* Loop Squareness for Evaporated Fe Thin Films: Effect of Substrates and Thickness

The switching field distribution (SFD) and the loop squareness, S*, are investigated for a series of evaporated Fe thin films grown onto single crystal Si(100), polycrystalline Al and amorphous glass substrates. The SFD and S* values have been inferred from hysteresis curves. The magnetization curves were obtained by means of a Vibrating Sample Magnetometer (VSM). The Fe thickness ranges from 76 to 431 nm. We discuss the effects of the substrates, the Fe thickness and grain size, and the temperature on the SFD and the squarness S*. A strong effect of the substrate on the SFD and S* values and behaviors is observed. The lowest SFD values are found in the Fe/Si(100) while the highest are measured in Fe/glass for the same Fe thickness. The correspondence between the SFD and the (1-S*) values is investigated.