The thickness dependence of structure, magnetic properties and read-write characteristics has been studied for sputtered iron oxide thin films prepared by RF reactive sputtering. For sputter-deposited Fe3O4 films, [111] preferential orientation perpendicular to film surface is improved and crystal size increases with an increase in thickness (δ). Magnetic properties for Fe3O4 films are affected by thickness. In particular, saturation magnetization rapidly decreases at thicknesses less than about 0.07 µm. From this perspective, it is concluded that a thickness larger than about 0.07 µm is available for practical use. For oxidation-annealed γ- Fe2O3 media, signal-output and media transition length are proportional to δ0.7 and δ0.5, respectively. A γ-(Co0.025Cu0.03Fe0.945)2O3 medium with a 0.071 µm thickness shows 0.51 mV of Epp, 2000 frpm of D-6 dB, -35 dB of O/W and 38 dB of SNR.

Gamma ferric oxide thin film media with a thickness of 0.190.27 µm were prepared by a reactive RF sputtering. Signal output loss with increasing temperature at high recording density was studies. Heating a medium-head system to 55 results in a 16% loss of signal output at 790 bpm (D-6 dB) of recording density for a medium having a 0.19 µm thickness; a 40% loss of signal output for a conventional-coated medium having a 0.7 µm thickness at 400 bpm (D-6dB), accompanying a decrease of a saturation write current value, IW(k-1) (an optimum write current). Increments of medium thickness and write current enhanced the thermal signal output loss. An over-saturated recording in the write process was suggested to cause the thermal signal output loss, especially for the thicker media. From the perspective of thermal stability of signal output at high recording density, sputtered γ-Fe2O3 thin film media are advantageous because of their thinness and small write current dependence of signal output.