拓扑绝缘体中的超快电荷自旋动力学

Ultrafast charge and spin dynamics on topological insulators

拓扑绝缘体是根据动量空间的拓扑不变量来定义的一类区别于普通绝缘体的新兴拓扑非平庸材料,其体态和表面态分别表现为绝缘和金属性质,并且其表面态具有独特的自旋结构(自旋-动量锁定),因此该类材料在光电器件和自旋电子器件领域有很多潜在的应用.由于开展这些应用研究首先需要对这类材料中的电荷与自旋动力学有全面的了解,所以拓扑绝缘体中的非平衡物理性质的研究引起了人们极大兴趣.本文对这一研究领域所作的研究工作做了一个较全面的描述,特别是跟时间分辨超快光谱相关的实验工作.并希望文中的讨论能激发研究者尤其是理论工作者对这一领域进一步的探讨,同时期待目标研究对象也能扩展到其他拓扑材料体系.

Topological insulators(TIs),with unique bulk insulating and two-dimensional surface conducting states,show great promise of future optospintronics and spintronics applications,where a complete knowledge of the charge and spin dynamics is quite essential.Thus,the non-equilibrium properties inside TIs have attracted enormous attention.Here in this paper,we review the latest achievements in this field.The focus will be mainly on the experimental study,covering the ultrafast dynamical properties of charge,phonon,and spin.We hope that this review can stimulate further studies,especially theoretical research concerning the properties of topological insulators out of thermodynamic equilibrium.