单晶Fe_3O_4超薄膜的制备与磁性研究

Preparation and magnetic properties of single crystal Fe_3O_4 ultra-thin film

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。

Ultra-thin Fe_3O_4 films with single crystal structure have been prepared by magneto sputtering method,and the effect of film thickness（3~30nm）on magnetic properties was systematically investigated.X ray diffraction results show that the Fe_3O_4 films grow along（220）crystal direction,and the full width at half maximum for（220）peak of Fe_3O_4 films becomes wider and wider with the film thickness decrease.Magnetization curves were clearly observed and the saturated magnetization intensity can be 400×103 A/m.The measurement of resistivity at low temperature confirms the Verwey transition from conductivity to insulator at around 120 K.It is seen that the surface roughness of Fe_3O_4 film is very low measured by atomic force microscopy,which indicate the Fe_3O_4 film is suitable for the development of nano-scaled spin electronic devices.