氧气分压对TiO_2薄膜结构、磁性及输运性质的影响

The effect of oxygen partial pressure on the structure,magnetism and transport properties of TiO_2 thin films

采用脉冲激光沉积技术在LaAlO_3(100)基片上制备了TiO_2薄膜,研究了氧气分压对薄膜结构、磁性与输运性质的影响.结构测量表明,TiO_2薄膜的结构与沉积过程中的氧气分压有关,氧气分压的增大有利于薄膜向锐钛矿相转变.磁性测量表明,在较高的氧气分压下制备的TiO_2薄膜表现为顺磁性,在较低氧气分压下制备的TiO_2薄膜表现出明显的室温铁磁性,其铁磁性与氧空位有密切关系.输运测量进一步表明,TiO_2薄膜表现为半导体导电特性,在具有铁磁性的薄膜中还观察到了低温磁电阻效应.

The TiO2 films are deposited on LaAlO3 （100） substrates using pulsed laser ablation. The effects of oxygen partial pressure on the structure, magnetism and transport properties of TiO2 films are studied systematically. A detailed analysis of the structural properties suggests that the crystal phase of TiO2 films depends on the oxygen partial pressure, the anatase phase increases for higher oxygen partial pressure. The magnetic measurement indicates that the films deposited at higher oxygen partial pressure shows paramagnetic, while, the well-defined hysteresis loops at room temperature can be clearly observed from the films deposited at lower oxygen partial pressure. The oxygen vacancies play an important role on the ferromagnetism of TiO2 films. The films exhibit the semiconducting behavior and positive magnetoresistances.