Permeability enhancement in Fe/CoNbZr multilayers prepared by Ar/H₂ mixed gas sputtering and heat treatment

Effects of layer thickness, deposition and annealing conditions on the magnetic properties of Fe/CoNbZr multilayers were investigated. When the multilayer comprising (Fe 40 nm/CoNbZr 10 nm) × 10 was deposited under Ar 80%/H₂ 20% (by volume), an increase in high frequency (100 MHz) permeability was observed (2300 from pure Ar deposition vs. 2900 from mixed gas deposition). Ar/H₂ mixed gas sputtering is believed to promote interface smoothness. Furthermore, when the same sample was annealed at 300°C for 30 min in a vacuum, we obtained even higher permeability reaching 3900 accompanying lower coercivity. Based upon X-ray diffraction analyses, annealing appeared to reduce residual stresses resulting in enhanced magnetic softness.