Magnetic domain structure control in patterned iron cobalt thin films using intrinsic and externally applied stresses

The increase in areal density in magnetic recording drives the need to change the magnetic materials used in recording heads to high magnetic saturation materials such as Fe65CO35. In this thesis; the effect of intrinsic and externally applied stress on the magnetic domain structures of patterned Fe65CO35 thin film elements was determined through experimental research and finite element analysis. A technique of determining the stress in patterned Fe65CO 35 structures with x-ray diffraction was developed which involves a thorough texture analysis to determine the volume fraction of grain orientations in the films and using stress measured via wafer curvature to determine the fraction of Reuss/Voigt interactions. This analysis can be used to accurately measure stress in patterned thin film elements. The presence of intrinsic stress in 1mum and 0.1mum thick patterned Fe65CO35 elements affected the direction of the easy axis in the 1mum thick structures, and the magnetic ripple amplitude in the 0.1mum thick structures. Energy calculations performed on domain walls and domain patterns indicate that a negative stress anisotropy is needed to change the easy axis in thick Fe 65CO35 structures. It was also shown that stress could be applied to a patterned Fe65CO35 structure with the addition of a piezoelectric BaTiO3 layer with an applied voltage. While this has not been verified experimentally, simulation results show that significant stresses can be induced in 0.1mum thick structures to change the magnetic ripple amplitude present in the structures.