Co掺杂GaN（0001）表面的能量学和磁性：第一性原理研究
Energetics and magnetism of Co-doped GaN(0001) surfaces: A first-principles stud
摘要：
采用第一性原理研究了Co掺杂GAN（0001）薄膜的能量、电子和磁性，揭示了表面结构对Co原子间磁耦合的影响。发现在不同的生长条件下，Co原子更倾向于取代表面Ga位。特别地，在富N和适度富Ga条件下，用Co原子替换第一Ga层的CoN/GAN界面结构是优选的，而发现CoGax/GAN界面在极度富Ga条件下是能量稳定的。值得注意的是，在清洁的GAN（0001）表面，Co原子之间的反铁磁耦合是有利的，但在Ga双层GAN（0001）表面，随着Co浓度的增加，FM的存在是可能的。我们的研究为Co掺杂GAN薄膜的实验研究提供了理论依据，并有望使Co：GAN系统在自旋注入器件中获得潜在的应用。
英文摘要：
A comprehensive first-principles study of the energetics, electronic and magnetic properties of Co-doped GaN(0001) thin films are presented and the effect of surface structure on the magnetic coupling between Co atoms is demonstrated. It is found that Co atoms prefer to substitute the surface Ga sites in different growth conditions. In particular, a CoN/GaN interface structure with Co atoms replacing the first Ga layer is preferred under N-rich and moderately Ga-rich conditions, while CoGax/GaN interface is found to be energetically stable under extremely Ga-rich conditions. It's worth noted that the antiferromagnetic coupling between Co atoms is favorable in clean GaN(0001) surface, but the existence of FM would be expected to occur as Co concentration increased in Ga-bilayer GaN(0001) surface. Our study provides the theoretical understanding for experimental research on Co-doped GaN films and might promise the Co:GaN system potential applications in spin injection devices.
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