Wang Ying, Luo Guoyu, Liu Junwei, Sankar R, Wang Nan-Lin, Chou Fangcheng, Fu Liang, Li Zhiqiang
National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.
College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan, 610064, China.
Nat Commun. 2017 Aug 28;8(1):366. doi: 10.1038/s41467-017-00446-2.
Topological crystalline insulators possess metallic surface states protected by crystalline symmetry, which are a versatile platform for exploring topological phenomena and potential applications. However, progress in this field has been hindered by the challenge to probe optical and transport properties of the surface states owing to the presence of bulk carriers. Here, we report infrared reflectance measurements of a topological crystalline insulator, (001)-oriented Pb Sn Se in zero and high magnetic fields. We demonstrate that the far-infrared conductivity is unexpectedly dominated by the surface states as a result of their unique band structure and the consequent small infrared penetration depth. Moreover, our experiments yield a surface mobility of 40,000 cm V s, which is one of the highest reported values in topological materials, suggesting the viability of surface-dominated conduction in thin topological crystalline insulator crystals. These findings pave the way for exploring many exotic transport and optical phenomena and applications predicted for topological crystalline insulators.Probing optical and transport properties of the surface states in topological crystalline insulators remains a challenge. Here, Wang et al. demonstrate that the far-infrared conductivity of Pb Sn Se (x = 0.23-0.25) single crystals is dominated by the surface states where carriers show a high surface mobility of 40,000 cm V s.
拓扑晶体绝缘体具有受晶体对称性保护的金属表面态，这是探索拓扑现象和潜在应用的通用平台。然而，由于体载流子的存在，探测表面态的光学和输运性质面临挑战，阻碍了该领域的进展。在此，我们报告了拓扑晶体绝缘体（001）取向的PbSnSe在零磁场和高磁场下的红外反射率测量结果。我们证明，由于其独特的能带结构以及由此产生的小红外穿透深度，远红外电导率意外地由表面态主导。此外，我们的实验得出表面迁移率为40000 cm V s，这是拓扑材料中报道的最高值之一，表明在薄拓扑晶体绝缘体晶体中表面主导传导的可行性。这些发现为探索拓扑晶体绝缘体预测的许多奇异输运和光学现象及应用铺平了道路。探测拓扑晶体绝缘体中表面态的光学和输运性质仍然是一个挑战。在此，王等人证明，PbSnSe（x = 0.23 - 0.25）单晶的远红外电导率由表面态主导，其中载流子表现出40000 cm V s的高表面迁移率。
