Department of Physics, East China Normal University, Shanghai 200062, People's Republic of China.
J Phys Condens Matter. 2012 May 30;24(21):215801. doi: 10.1088/0953-8984/24/21/215801. Epub 2012 Apr 27.
The influence of external strain on the diffusion barriers of interstitial Mn in GaAs is studied using the first-principles calculations within the density functional theory. The diffusion barrier changes with strain in different manners: linear on the tensile strain and nonlinear on compressive strain, in contrast to the linear behavior of the continuum elastic model. The discrepancy between the continuum elastic model and the results of the first-principles method is attributed to the energy-level crossing caused by strain. Moreover, we find that the external strain can not only effectively change the diffusion barrier (even to zero, at certain strain), but also the position of saddle points along the migration path. Our finding provides an alternative way to reduce the population of interstitial Mn in GaAs, thus correspondingly to increase the Curie temperature of this system.
利用第一性原理密度泛函理论计算研究了外应变对 GaAs 中间隙 Mn 扩散势垒的影响。扩散势垒随应变的变化方式不同：拉伸应变呈线性，压缩应变为非线性，与连续弹性模型的线性行为相反。连续弹性模型与第一性原理方法结果之间的差异归因于应变引起的能级交叉。此外，我们发现外应变不仅可以有效地改变扩散势垒（甚至在某些应变下降至零），还可以改变迁移路径上鞍点的位置。我们的发现为降低 GaAs 中间隙 Mn 的浓度提供了一种替代方法，从而相应地提高了该体系的居里温度。
