非均匀Fe-Ti-O磁性半导体薄膜的结构、磁性和电输运特性

发布时间：2018-03-12 11:49

本文选题：薄膜　切入点：溅射　出处：《天津理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：非均匀磁性半导体薄膜是一种同时具备半导体性质和磁性质的薄膜材料,是最有可能实现自旋电子器件实际应用的材料之一。这类薄膜主要通过向半导体中掺杂磁性离子来制备。人们先后在磁性金属非磁性金属多层膜系统、磁性金属绝缘体颗粒系统以及磁性隧道结中发现了室温下的磁电阻效应(GMR),并努力将这种非本征的电子输运特性应用到电子学器件中。GMR效应来源于电子的自旋相关散射或自旋相关的隧道效应,即与两个相邻磁性单元的磁化强度的相对取向以及传导或隧道电子的自旋极化率有关。因此,近年来,非均匀磁性体系的磁性、结构及自旋相关的电子输运特性的研究是电子材料和器件领域最为活跃的研究课题之一。本论文中采用磁控溅射的方法制备了非均匀的FexTi1-xOδ磁性半导体薄膜,并对制备的FexTi1-xOδ系列薄膜的微结构、磁性质及电输运性质进行了详细的表征和分析。研究表明所制备的薄膜是非结晶态的,且薄膜内各种元素的分布是不均匀的。所有的样品在低温时都具有明显的铁磁性特征;温度为5 K时,样品的矫顽力超过600 Oe,磁化强度的最大值超过1000 emu/cm3;室温时,样品的矫顽力与剩磁都减小为0,磁化强度的最大值减少为410 emu/cm3。对样品的电输运性质研究表明:所制备薄膜的电输运特性为可变程跃迁导电机制,温度为3 K时,样品中最大的负磁电阻值为32%;室温下,磁电阻仍为8%,并且为负值。低温时的负磁电阻效应是由薄膜的无序磁矩的反铁磁性造成的。
[Abstract]:Nonuniform magnetic semiconductor film is a kind of thin film material with both semiconductor and magnetic properties. It is one of the most promising materials for the practical applications of spin electronic devices. These thin films are prepared mainly by doping magnetic ions into semiconductors. The magnetoresistance effect at room temperature has been found in the magnetic metal insulator particle system and magnetic tunnel junctions. The application of this non-intrinsic electron transport characteristic to the electronic devices. GMR effect originates from the spin of electrons. Tunneling effects related to scattering or spin, That is, the relative orientation of magnetization of two adjacent magnetic units and the spin polarizability of conducting or tunneling electrons. Therefore, in recent years, the magnetic properties of inhomogeneous magnetic systems, The study of the structure and spin related electron transport characteristics is one of the most active research topics in the field of electronic materials and devices. In this thesis, the nonuniform FexTi1-xO 未 magnetic semiconductor thin films are prepared by magnetron sputtering. The microstructure, magnetic properties and electrical transport properties of the FexTi1-xO 未 series films are characterized and analyzed in detail. The results show that the films are amorphous. And the distribution of various elements in the film is not uniform. All the samples have obvious ferromagnetic characteristics at low temperature. At 5 K, the coercivity of the sample exceeds 600 OE, the maximum magnetization is more than 1000 emu / cm 3, and at room temperature, The coercivity and remanence of the samples are reduced to 0, and the maximum magnetization decreases to 410 emu / cm 3. The study of the electrical transport properties of the films shows that the electric transport characteristics of the films are variable range transition conduction mechanism, and the temperature is 3 K. The maximum negative magnetoresistance in the sample is 32 and the magnetoresistance is still 8 and negative at room temperature. The negative magnetoresistance effect at low temperature is caused by the antiferromagnetism of the disordered magnetic moment of the thin film.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304;TB383.2

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