Domain optimization of sputtered permalloy shields for recording heads

NiFe single layer and multilayer films laminated with amorphous Al ₂O₃ interlayers were deposited by DC magnetron sputtering. The total ferromagnetic layer thickness was constant 1800 nm for the single and four layer lamination. Full film magnetic characterization revealed comparable soft magnetic properties for all samples. However, patterning the samples led to completely different domain and domain wall characteristics depending on the interlayer thickness. Influences of existing perpendicular anisotropy were observed by magneto-optical Kerr microscopy in the domain walls and closure domains of the structured samples. With increasing Al₂O₃ thickness the influence of perpendicular anisotropy on the domain patterns was reduced. At the largest interlayer thickness, the magnetization in each ferromagnetic layer behaves independently. The observed micromagnetic structures will be discussed