Fe_3O_4(100)/STO(100)薄膜的制备及磁输运特性研究

Preparation of Fe_3O_4(100)/STO(100) Thin Film and Its Magneto Transport Characteristics

采用脉冲激光沉积方法,以烧结的Fe3O4为靶材,在STO(100)基底上制备了Fe3O4(100)薄膜。XRD和AFM显示薄膜为纯相外延单晶薄膜、表面较平整。对薄膜的磁电阻进行测量,薄膜为负磁电阻,且在Verwey转变温度(约120 K)时磁电阻最大。霍尔效应测量得到薄膜中载流子浓度随着温度的降低而减小,ln(n)与1/T基本呈线性关系,符合半导体热激活模型,迁移率随着温度的降低而减小,说明在薄膜内存在大量电离杂质中心。薄膜磁滞回线中较高的饱和磁化场,说明薄膜中APBs密度较低。

Epitaxial Fe3O4（100） thin films were deposited on SrTiO3（100） substrates by PLD, using sintered Fe3O4 polycrystalline target. XRD and AFM results demonstrate the good flatness and pure phase of the epitaxial thin film. The film shows a negative magnctoresistance with a maximum at the Verwey transform temperature （120 K）. Carrier density of the film calculated fi＇om Hall effect results decrease with the temperature lowering. In （n） has a linear relation with 1/T basic, in accordance with semiconductor thermal activation model. The mobility decreases with the temperature lowering, demonstrat- ing the high ionized impurity density in the film. The high saturation field deduced from the magnetic hysteresis suggests the low APBs density in the film.