Gd掺杂ZnO纳米线磁耦合性质的第一性原理研究

Magnetic coupling properties of Gd-doped ZnO nanowires studied by first-principles calculations

本文利用基于密度泛函理论的第一性原理方法计算了钆(Gd)掺杂氧化锌(ZnO)纳米线的磁耦合特性.讨论了两个Gd原子替换ZnO纳米线中不同位置Zn原子的各种可能情况.计算发现,ZnO中掺杂的Gd原子处于相邻的位置时它们之间的相互作用是铁磁性的,并且体系的铁磁性可以通过注入合适数目的电子来得到加强.同时发现Gd掺杂ZnO纳米线后s-f耦合作用变得显著,使得体系的铁磁性变得更加稳定,这也是Gd掺杂ZnO纳米线呈现铁磁性的原因.这些结果为实验上发现的Gd掺杂ZnO纳米线呈铁磁性提供了理论依据.

Magnetic coupling properties of Gd-doped ZnO nanowires are studied theoretically by using first-principles calcu-lations. Several positions of Zn atoms that may be substituted by Gd atoms in ZnO nanowires are discussed. Numerical results show that the magnetic coupling is ferromagnetic when the two Gd atoms doped in ZnO nanowires are near each other. Injection of suitable amount of electrons can enforce these ferromagnetic properties in Gd-doped ZnO nanowires. It is also found that s-f coupling becomes remarkable when the Gd atoms are doped in ZnO nanowires, making the ferromagnetic coupling state more stable than the anti-ferromagnetic coupling state, and this is also the mechanism to elucidate the origination of ferromagnetic state in Gd-doped ZnO nanowires in experiments. These results will give a theoretical support for those who found experimentally that Gd-doped ZnO nanowires show ferromagnetic properties.