二氧化铈基稀磁氧化物的第一性原理研究

基于第一性原理的计算方法研究了纯CeO_2、Co掺杂CeO_2和同时引入氧空位Vo和Co掺杂的CeO_2稀磁半导体体系.通过计算体系的能带结构和态密度,探讨了该体系磁性产生的机制.计算发现,纯CeO_2体系不具有磁性;没有氧空位Vo的Co掺杂CeO_2体系中,Co离子之间通过O原子发生超交换反铁磁耦合,体系无铁磁性;当氧空位Vo和Co离子同时存在于CeO_2体系中时,Co离子之间通过氧空位Vo发生铁磁耦合,该体系表现出铁磁性能.另外,由氧空位Vo诱导的Co离子之间的铁磁耦合不仅发生在紧邻的两个Co离子,而且可以扩展到几个原子距离的长度.计算结果证明了氧空位Vo诱导铁磁性耦合机制.本文工作将为CeO_2基稀磁半导体体系制备与磁学性质的研究提供支持.

First-principles Study of CeO2 based diluted magnetic oxide

Based on the first-principles calculation method, diluted magnetic semiconductors 0f the pure CeO2, Co doped CeO2 and Co doped CeO2 with oxygen vacancy Vo were studied. Through the calculation of the energy band structure and density of states, the origination of magnetism of the system is discussed. Calculations show that the pure CeO2 system does not have magnetism; Co doped CeO2 system without oxygen vacancies Vo has no ferromagnetism since Co ions form anti-ferromagnetic exchange coupling via O atoms; Co doped CeO2 system with oxygen vacancies Vo, Co ions form ferromagnetic exchange coupling via oxygen vacancies Vo, the system exhibits ferromagnetism. In addition, the ferromagnetic exchange coupling between Co ions induced by the oxygen vacancy Vo not only took place in two adjacent Co ions, but alao can be extended to several atomic distances. The results show that the oxygen vacancy Vo induces ferromagnetic exchange coupling mechanism. This work will provide support for the preparation and magnetic property studies of CeO2 based diluted magnetic semiconductors.