Magnetic properties and film structures of Fe/C multilayers

The magnetic properties and film structures of Fe/C multilayers (period: 5–50 nm) formed by ion beam sputtering are studied. The coercivity in the easy axis direction is decreased from 380 A/m (=4.8 Oe) to 25 A/m (=0.3 Oe) by reducing the period from 50 to 5 n. The relative permeability increases to a maximum of approximately 3000 with increasing C layer thickness. Cross‐sectional transmission electron microscopy and Auger electron spectroscopy show that Fe layers are clearly separated by C layers, resulting in small Fe crystallites.