Studies On Microstructures And Magnetic Properties Of FeCo Thin Films

With the rapid development of the high density recording, it is required that the magnetic head materials have very high saturation magnetic flux density. Fe-Co alloys have been intensively investigated because of their very high saturation flux density. Sputter deposited Fe-Co films, however, generally show high coercivity and they are therefore not applicable as the write pole materials in a magnetic recording head.In this thesis, some series films were prepared by dc magnetron sputtering onto glass substrates at room temperature. Microstructures of films were examined by X-ray diffraction (XRD). Morphologies and domain structures were observed by scanning probe microscope (SPM). And magnetic properties were measured by vibrating sample magnetometer (VSM). The influence of sputtering parameter on their microstructure and magnetic properties were studied, respectively.1. Influences of the fabrication conditions on microstructures and magnetic properties of Fe₅₀Co₅₀ thin films(1) The annealing temperatures were found to be helpful for reducing the coercivity. For the Fe₅₀Co₅₀ (50 nm) film, the minimum value of Hc is obtained about 70 Oe at T_a=600℃, with the saturation magnetization being 1314emu/cc.(2) The coercivity firstly reduces and then increases with annealing temperature increasing. The coercivity reaches the minimum 27Oe for the Fe₅₀Co₅₀ (50nm) film at the substrate temperature of 400℃. SPM image shows the average grain size increases with the substrate temperature increasing.(3) It is found that the coercivity of Fe₅₀Co₅₀ films firstly increases and then reduces with the film thicknesses increasing. The maximum value of coercivity is obtained when the thickness of Fe₅₀Co₅₀ films was 30nm. SPM image shows the average magnetic domains size reduces with increasing the thickness.(4) The coercivity of reaches the minimum 15 Oe for the Fe₅₀Co₅₀ (10 nm) film at the annealing temperature of 600℃for 2h. 2. Influences of the fabrication conditions on microstructures and magnetic properties of Fe₃₀Co₇₀ thin films(1) The annealing temperature was found to be helpful for reducing the coercivity. For the Fe₃₀Co₇₀ (50nm) film, the minimum value of Hc is obtained about 44Oe at Ta=650℃, with the saturation magnetization being 975emu/cc.(2) The coercivity firstly reduces and then increases with the substrate temperature increasing. The coercivity reaches the minimum 16Oe for the Fe₃₀Co₇₀ (50nm) film at the substrate temperature of 300℃. SPM images show the average grain size increases with increasing the substrate temperature.(3) It is found that the coercivity of Fe₃₀Co₇₀ films firstly increases and then reduces with the film thicknesses increasing. The maximum value of coercivity is obtained when the thicknesses of Fe₃₀Co₇₀ films was 100 nm.(4) The coercivity reaches the minimum 15Oe for the Fe₃₀Co₇₀ (10 nm) film at the annealing temperature of 600℃for 2h.3. Influences of the fabrication conditions on microstructures and magnetic properties of Fe₇₀Co₃₀ thin films(1) It is found that the coercivities of Fe₇₀Co₃₀ films firstly increase and then reduce with the film thicknesses increasing. The maximum value of coercivity is obtained when the thicknesses of Fe₇₀Co₃₀ film is 30nm.(2) For the Fe₇₀Co₃₀ (10 nm) film, the minimum value of Hc is obtained about 18Oe at Ta=600℃, with the saturation magnetization being 1602emu/cc.(3) The coercivity firstly reduces and then increases with substrate temperature increasing. The coercivity reaches the minimum 13.5Oe for the Fe₇₀Co₃₀ (10 nm) film at the substrate temperature of 300℃.