非磁性/磁性掺杂剂对SnO2体系的性能调控

本文通过第一性原理计算在GGA + U 框架下系统地研究了非磁性掺杂剂(Li)和磁性掺杂剂(V)以及相应的点缺陷(VO/VSn)掺杂SnO2基稀磁半导体(DMS)的稳定性、电子结构、键合性质、磁性以及光学性质. 计算得到的形成能结果表明, V元素单掺杂体系比Li元素单掺杂体系更稳定. 其中, VO存在的掺杂体系稳定性更高, 而VSn对掺杂体系的稳定性不利. 磁性分析表明, Li掺杂体系的磁矩大于V掺杂体系的磁矩. 当有点缺陷存在时, VSn的加入显著提高了掺杂体系的磁性, 而VO对非磁性金属元素/磁性金属元素掺杂体系的磁性影响不同：当VO存在于Li掺杂体系时, Li原子周围的O原子自旋极化减少, 因此导致磁矩降低；当V掺杂体系中有VO存在, 磁性不仅来源于V原子的自旋极化, 同时来源于VO周围的O原子的自旋极化,因此磁矩增大. 结合电子结构分析可知, Li掺杂体系的磁性是由O-p和Li-p轨道之间的双交换作用产生的, V掺杂体系的磁性是由O-p和V-d轨道之间的双交换作用产生的. 键合分析发现VO的存在可以提高两种金属掺杂体系键(Li-O和V-O)的共价性. 在可见光区域内, Sn15LiO32和Sn15VO32具有较高的光学透明度. 以上这些结果为非磁性金属元素(Li)和磁性金属元素(V)及相应的点缺陷(VO/VSn)掺杂SnO2在自旋电子器件中的应用提供了新的思路.

The optimal tuning of SnO2 systems by non-magnetic dopant/magnetic dopant

In this paper, the stability, the electronic structure, the bonding stations, as well as the magnetic and optical properties of non-magnetic dopants (Li), magnetic dopants (V), and the corresponding point defects (VO/VSn) on SnO2-based dilute magnetic semiconductors (DMS) are systematically investigated through ab-initio calculations. All the calculations are carried out within the GGA + U framework. The calculated formation energy results showed that the V single-doped system is more stable than the Li single-doped system. Among them, the doping system with VO had higher stability, while VSn was unfavorable for the stability of the doping system. The magnetic analysis showed that the magnetic moment of the Li-doped system is larger than that of the V-doped system. The addition of VSn significantly improved the magnetic properties of the doped system, while the presence of VO had different effects on the magnetic properties of the non-magnetic metal element/magnetic metal element doped system. When VO is present in the Li-doped system, the spin polarization of the O atoms around the Li atom is reduced, thus leading to a lower magnetic moment. When VO is set in the V-doped system, the magnetic moment increases not only from the spin polarization of the V atom but also from the spin polarization of the O atoms around VO. Combined with the electronic structure analysis, it is clear that a spin-polarized double exchange effect in the Li-p and O-p orbitals, which leads to magnetism of the Li-doped system, and the magnetism of the V-doped system is generated by the spin-polarized double exchange effect between the O-p and V-d orbitals. The bonding analysis revealed that the presence of VO enhances the covalency of the bonds (Li-O and V-O) of the two metal-doped systems. In the visible region, Sn15LiO32 and Sn15VO32 had relatively high optical transparency. These results provided new ideas for the application of non-magnetic metal elements (Li), magnetic metal elements (V), and the corresponding point defects (VO/VSn) doped SnO2 in spintronic devices.