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采用磁控溅射方法制备了单晶Fe_3O_4超薄膜,系统研究了厚度(3~30nm)对薄膜磁性的影响。X射线衍射证明了Fe_3O_4单晶薄膜是(220)晶向,(220)衍射峰的半高全宽和晶格常数随薄膜厚度的下降而增大。磁性测量观察到了清晰的磁滞回线,饱和磁化强度达400×103 A/m。低温电阻率测量证实了薄膜在120K温度附近发生了导体向绝缘体的Verwey转变。利用原子力显微镜观察到Fe_3O_4薄膜的表面粗糙度非常低,适用于纳米尺度自旋电子学器件的开发。
The single crystal Fe_3O_4 ultrafilm was prepared by magnetron sputtering. The influence of the thickness (3 ~ 30nm) on the magnetic properties of the film was systematically investigated. X-ray diffraction shows that the (220) crystal orientation of the Fe 3 O 4 single crystal film shows a decrease in the full width at half maximum (FWHM) and the lattice constant of the (220) peak as the film thickness decreases. A clear hysteresis loop was observed in the magnetic measurement, with a saturation magnetization of 400 × 10 3 A / m. Low temperature resistivity measurement confirmed that the film produced a Verwey transition from insulator to insulator near 120K. The atomic force microscopy shows that the surface roughness of Fe_3O_4 thin films is very low and is suitable for the development of nanoscale spintronic devices.