In-plane magnetic anisotropy induced in spin-sprayed Ni-Zn-Co ferrite films exhibiting strong magnetic loss at gigahertz range

Ni-Zn(-Co) ferrite films of 0.5-0.6 /spl mu/m in thickness were deposited on glass substrates by the spin-sprayed ferrite plating at as low as 90/spl deg/C applying external magnetic field of 50 Oe. Under no bias field, while the film without Co substitution (Ni/sub 0.21/Zn/sub 0.27/Fe/sub 2.52/O/sub 4/) exhibited a relatively high coercivity H/sub c/ of about 27 Oe, it decreased to 15 Oe for Co substituted film (Ni/sub 0.21/Zn/sub 0.27/Co/sub 0.04/Fe/sub 2.48/O/sub 4/), and a slight uniaxial anisotropy was induced along the liquid flow direction of sprayed solutions. The decrease in H/sub c/ was attributed to the anisotropy compensation originated by Fe/sup 2+/ and Co/sup 2+/. Under bias field of 50 Oe, a definite in-plane magnetic anisotropy was induced in the Co substituted film. The imaginary permeability /spl mu/'' was greater than 20 over a wide frequency range from 300 MHz to 3 GHz. Since the product of /spl mu/''/spl times/f, which is proportional to the absorption of conducted noise, increased even in gigahertz range reaching the peak at 1.7 GHz, Ni-Zn-Co ferrite films with in-plane uniaxial anisotropy are applicable as shielding materials for suppressing electromagnetic interference in gigahertz range.