Soft Magnetic Properties of Co-Nb-Ta-Zr Amorphous Films Deposited on Polyimide Films

Co-Nb-Ta-Zr amorphous films were fabricated on polyimide sheets. Thermal changes of the coercive force and uniaxial anisotropy field were investigated in order to determine annealing conditions by which the magnetic softness is improved. The amorphous films on polyimide sheets were found to exhibit good magnetic softness, comparable to that of films on glass substrates. Based on these results, sheets were wound around a Cu bobbin and after annealing in a dc or rotating magnetic field, the frequency dependence of the initial permeability was measured. An initial permeability as high as 2500, with little decay up to 30 MHz, was obtained.