N掺杂SiO_2纳米薄膜的制备及其磁性

Preparation and magnetism of the N doped SiO_2 thin film

利用射频磁控反应溅射技术,制备了氮掺杂的SiO2纳米薄膜.发现N掺杂SiO2体系纳米薄膜具有铁磁性.较小的氮化硅颗粒均匀分布在氧化硅基质中有利于磁有序的形成.基底温度为400℃时,样品薄膜具有最大的饱和磁化强度和矫顽力,分别为35emu/cm3和75Oe.薄膜的磁性可能产生于氮化硅和氧化硅的界面.理论计算表明,N掺杂SiO2体系具有净自旋.同时,由氮化硅和氧化硅界面之间的电荷转移导致的轨道磁矩也会对样品的磁性有贡献.

The N doped SiO2 thin films were prepared by radio frequency magnetron reaction sputtering technique. It is found that the N doped SiO2 thin films have ferromagnetism. Magnetic order is easy to form in the system in which silicon nitride particles with relatively small sizes are distributed uniformly in silicon oxide matrix. When the substrate temperature of the film was 400℃ ,the N doped SiO2 thin film possesses the largest saturation magnetization and coercivity,being 35 emu /cm3 and 75 Oe,respectively. The magnetism of the film may originate from the interfaces between silicon nitride and silicon oxide. Calculations based on the first principles show that net spins exist in the N doped SiO2 film. The orbit magnetic moments caused by the charge transfer through the interface between silicon nitride and silicon oxide also contribute to the ferromagnetism of the film.