FERROMAGNETIC-RESONANCE IN COBALT-MODIFIED IRON-OXIDE PARTICULATE TAPES

The magnetic anisotropy field (H-a) of Co-modified-Fe3O4 acicular part icles in particulate tapes was studied using ferromagnetic resonance. The value of H-a of the particles has been determined to be 3.50 kOe, assuming a saturation magnetization (M) of 0.398 kG. Since the anisotr opy field due to the acicular shape anisotropy is calculated to be 2.3 4 kOe for the particles with an axial ratio of 10, the contribution to H-a of the Co modification on the particle surface is estimated to be 1.16 kOe.