Minimum Thermal Conductivity in Weak Topological Insulators with Bismuth‐Based Stack Structure. (25th May 2016)

• Record Type: Journal Article
• Authors: Wei, Ping; Yang, Jiong; Guo, Liang; Wang, Shanyu; Wu, Lihua; Xu, Xianfan; Zhao, Wenyu; Zhang, Qingjie; Zhang, Wenqing; Dresselhaus, Mildred S.; Yang, Jihui
• Is Part Of: Advanced functional materials. Volume 26:Number 29(2016)
• Page Start: 5360
• Page End: 5367
• Publication Date: 2016-05-25
• Subjects: lattice dynamics -- minimum thermal conductivity -- thermoelectrics -- topological insulator; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201600718
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract : Contrary to the conventional belief that the consideration for topological insulators (TIs) as potential thermoelectrics is due to their excellent electrical properties benefiting from the topological surface states, this work shows that the 3D weak TIs, formed by alternating stacks of quantum spin Hall layers and normal insulator (NI) layers, can also be decent thermoelectrics because of their focus on minimum thermal conductivity. The minimum lattice thermal conductivity is experimentally confirmed in Bi14 Rh3 I9 and theoretically predicted for Bi2 TeI at room temperature. It is revealed that the topologically "trivial" NI layers play a surprisingly critical role in hindering phonon propagation. The weak bonding in the NI layers gives rise to significantly low sound velocity, and the localized low‐frequency vibrations of the NI layers cause strong acoustic–optical interactions and lattice anharmonicity. All these features are favorable for the realization of exceptionally low lattice thermal conductivity, and therefore present remarkable opportunities for developing high‐performance thermoelectrics in weak TIs. Abstract : Inspired by the fascinating crystal structure of weak topological insulators featuring an alternating stack of 2D quantum spin Hall layers and normal insulator layers, the discovery of the intrinsic minimum lattice thermal conductivity occurring near room temperature and strongly anharmonic lattice dynamics in this kind of novel materials provides an intriguing pathway for the exploration of highly efficient thermoelectric materials.