The solid solution system ilmenite-hematite [(FeTiO3)1−x–(Fe2O3)x] is a potential candidate for applications in spintronics due to its intrinsic ferrimagnetic and semiconducting properties. Epitaxial ilmenite-hematite films with x=0.33, which have the highest room temperature magnetic moment, were grown on α-Al2O3 (0001) substrates using pulsed laser deposition technique with varying oxygen partial pressure in the ambient gas. Structural, magnetic, electrical, and optical properties are found to be largely dependent on the oxygen content of the films which is controlled by substrate temperature and ambient gas composition. The highest crystalline and magnetic ordering and the lowest resistivity values could be obtained for growth at high temperatures and under low oxygen pressure. A narrowing of the band gap (to around 2.4eV) was observed for films grown under high oxygen pressure in comparison with films grown in vacuum or argon (around 3.3eV).
Ilmenite-hematite [(FeTiO3)1−x–(Fe2O3)x] is a solid solution system with intrinsic ferrimagnetic and semiconducting properties. Bulk ceramic samples and epitaxial thin films have been prepared with magnetization values of up to 1500G (bulk) and 700G (thin films) at room temperature. Superparamagnetic behavior was discriminated from ferrimagnetic properties using field cooled and zero field cooled measurements. The blocking temperature exceeds room temperature for samples with composition x>0.25. Using magnetic force microscopy, the domain structure in the thin ilmenite-hematite films was detected.
Ultrasonic was introduced during pulse plating process to prepare NiFeP alloy films. Effects of different duty ratios and ultrasonic powers on composition, microstructure and magnetic properties of films were investigated. With the rise in duty ratios, the amount of nickel increased gradually. Higher ultrasonic power could result in larger contents of iron in NiFeP alloy films. That was because nickel reduction was potential controlled while iron reduction was diffusion controlled during the pulse plating process. Almost all the deposited films were crystalline and formed peaks of FeNi 3 (111), FeNi 3 (200) and FeNi 3 (220). With the increase in duty ratios, the intensity of all three peaks started to decline, which led to worse crystalline and bigger grain sizes. Dissimilar surface morphology could be detected by the condition of different duty ratios and ultrasonic powers. NiFeP films with smaller grain size and smooth surface could be obtained when a higher power of ultrasonic was introduced during the pulse plating process. However, the films with rough and agglomerate nodular structures would be observed with higher duty ratios. Vibration sample magnetometer results showed that the coercivity of NiFeP films ranged from 30 to 150 Oe.
CoWP alloy films were prepared by a typical citrate system electrodeposition on a copper substrate. The paper investigated effects of different temperatures on codeposition mechanism, magnetic property, component and structure of CoWP alloy films during the electrodeposition process. With the increase in temperatures, deposition rate and thickness rose gradually during the electrodeposition process. It was found that higher temperature improved contents of phosphorus and tungsten but reduced amounts of cobalt in the films. Almost all the deposited films were crystalline and formed tetrahedral structures Co 3 W with preferred crystallographic orientation (200) and (201). Films of dissimilar surface morphology could be observed under different temperatures. Lower saturation magnetisation and higher coercivity of CoWP films could be obtained at higher temperatures.
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