中文摘要：

采用第一性原理计算方法，研究了四方MoSi2薄膜的电子性质．计算结果表明，各种厚度的薄膜都是金属性的，并且随着厚度的增加，其态密度与能带结构都逐渐趋近于MoSi2块体的特性．通过对MoSi2薄膜磁性的分析，发现三个原子层厚的薄膜具有磁性，其原胞净磁矩为0．33μB；而当薄膜的厚度大于三个原子层时，薄膜不具有磁性．此外，进一步对单侧加氢饱和以及双侧加氢饱和结构下三原子层MoSi2薄膜的电子性质进行了研究，发现单侧加氢饱和的三原子层MoSi2薄膜具有磁性，其原胞净磁矩为0．26μB，而双侧加氢饱和三原子层MoSi2薄膜是非磁性的．双侧未饱和与单侧加氢饱和的三原子层MoSi2薄膜的自旋极化率分别为30％和33％．这些研究结果表明，三原子层厚的MoSi2超薄薄膜在悬空或者生长于基底之上时具有金属磁性，预示着它在纳米电子学和自旋电子学器件等方面都有潜在的应用前景．

英文摘要：

Electronic properties of tetragonal MoSi2 thin films are studied by the first-principles method. The results show that the MoSi2 film is always metallic, and its density of states and electronic structure are gradually close to their bulk counterpart as the film thickness increases. We further show that the three-atomic-layer film with the lowest energy is magnetic and has a magnetic moment of 0.33 μB for its unit cell, and the film becomes non-magnetic when its thickness is more than three atomic layers. Moreover, we investigate the electronic properties of the three-atomic-layer MoSi2 films under unilateral and bilateral hydrogenation and find that the film with unilateral hydrogenation is magnetic and has a magnetic moment of 0.26 μB, while the film with bilateral hydrogenation is non-magnetic. The spin polarizations for the films without hydrogenation and unilateral hydrogenation are 30% and 33%, respectively. These results suggest that three-atomic-layer MoSi2 film is metallic or magnetic when it is under suspension or grown on substrate, indicating its potential applications in nanoscale electronic and spintronic devices.