Enhancement of high frequency permeability in amorphous CoNbTi/SiO2layered films

In regard to magnetic recording head material, the Co80Nb10Ti10/SiO2and Co88Nb6Ti6/SiO2multilayered films produced by a dual sputtering technique have been examined. The magnetic CoNbTi layers were in the amorphous state and nearly zero magnetostrictive, while the insulating SiO2layers were formed into the crystalline compound. It has been found that dc-coercivity and permeability at low frequency are respectively increased and decreased with decreasing CoNbTi thickness. However, these values can be improved by layering with a thin SiO2inter layer. In addition, the permeability at high frequency can be enhanced by perpendicular field-annealing up to the level of 5,000- 10,000 at 10 MHz. In the Co80Nb6Ti6/SiO2multilayered films having 11 kG of the saturation magnetization Bs, about 9,200 of the initial permeability at 1 mOe of the exciting field has been obtained in the range from 1 kHz to 10 MHz.