Magnetic orientation of iron films produced by laser-deposition

利用穆斯堡尔光谱和扫描电镜研究了沉积在Al衬底上的铁膜。结果表明，经电阻加热汽化的铁原子沉积制备的铁膜的核自旋取向与基底表面垂直，而激光沉积制备的铁膜的核自旋取向与基底表面平行。激光沉积所产生的液滴呈圆盘状，并扰乱薄膜的自旋方向。我们已经证明了采用不同的沉积方法可以控制铁膜的自旋取向。将黄铁矿（FeS_2）和赤铁矿（Fe_2O_3）激光沉积在Al或SiO_2/Si衬底上。样品的穆斯堡尔光谱提供了激光沉积薄膜组成的信息。在较高温度下制备的样品具有较少的S原子组成的磁性FeS，而在较低温度下制备的样品具有接近FeS_2的成分。在这两种情况下，得到了晶格结构中有缺陷的样品。SiO_2/Si衬底比Al衬底更能稳定FeS_2相。扫描电镜（SEM）观察到，在较低温度下得到了反映FeS_2沉积成分的液滴颗粒。激光沉积Fe_2O_3的初步结果表明，制备的FeO和Fe_2O_3颗粒具有很高的晶体缺陷密度。结果表明，激光沉积的化合物可以产生与激光蒸发材料具有不同化学物质的薄膜。研究还表明，薄膜中产物化合物的产率随衬底温度的变化而变化。

Iron films deposited on Al substrates were investigated using Mossbauer spectroscopy and scanning electron microscopy. It was found that the nuclear spin orientation of iron films produced by deposition of Fe atoms vaporized by resistive heating was perpendicular to the substrate surface, while that of films produced by laser deposition of Fe was parallel to the substrate surface. The droplets produced by laser deposition have a disk-like shape and perturb the spin orientation of the film. We have demonstrated that the spin orientation of Fe films can be controlled by employing different deposition methods.Pyrite (FeS_2) and hematite (Fe_2O_3) were laser-deposited on Al or SiO_2/Si substrates. Mossbauer spectra of the samples provided information on composition of the laser-deposited films. The samples produced at higher temperatures have compositions with fewer amounts of S atoms to have magnetic FeS, whereas the samples produced at low temperatures have compositions close to FeS_2. In both cases, samples with defects in the lattice structure were obtained. A SiO_2/Si substrate was found to stabilize FeS_2 phase better than an Al substrate. From SEM images, it was observed that droplet particles which reflect the as-deposited composition of FeS_2 were obtained at a lower temperature. The preliminary results on laser-deposition of Fe_2O_3 show that FeO and Fe_2O_3 particles with a very high density of crystal defects were produced. It was shown that laser-deposition of compounds can produce films that have different chemical species than the laser-evaporated materials. It was also shown that yields of product compounds in films vary depending on the temperature of the substrate.