Structure, Magnetic And Electronic Transport Properties Of Non-uniform Fe-Ti-O Magnetic Oxide Semiconductor Films

Non-unifirm magnetic semiconductor films are a kind of film materials along with semiconductor and magnetic properties, may be one of the most likely materials can realize applications in spintronic device. Such films are mainly fabricated by doping magnetic ions into the semiconductor materials. Researchers successively observed the magnetoresistance effect(GMR) at room temperature in magnetic metal/nonmagnetic metal multilayers, magnetic metal insulator granular system and magnetic tunnel junction, and try to use the extrinsic electron transport properties in the spintronics devices. The origin of GMR is commonly attributed to the electron spin related scattering or spin tunnel effect, related to relative magnetization orientation of two adjacent magnetic units and the spin polarization of conduction or tunneling electrons. Therefore, recently, magnetic, structure, and spin-dependent electronic transport properties in the non-uniform magnetic systems are one of the most hot topics in the field of electronic materials and devices.In this work, we adopted the magnetron sputtering to prepare the non-uniform FexTi1-xOδ magnetic semiconductor films, and investigated the microstructure, magnetic and electric transport properties of FexTi1-xOδ films. The characterizations have been analyzed and discussed in details.The results show that all the prepared FexTi1-xOδ samples are amorphous and the distribution of the elements are non-uniform. All the films are ferromagnetic at low temperature. At 5 K, the maximum coercivity is larger than 600 Oe, and the saturation magnetization is 1000 emu/cm3. At room temperature, both coercivity and remanent magnetization of the films reduce to zero, and the saturation magnetization is 410 emu/cm3. The results of electrical transport characterizations indicate that the mechanism of all the films are variable range hopping conductance. At 3 K, the negative magneto-resistance reaches 32%, and at room temperature, a 8% negative magneto-resistance appears. The large low-temperature negative magnetoresistance effect can be ascribed to the antiferromagnetically coupled disorder moments.