Minimum Thermal Conductivity in Weak Topological Insulators with Bismuth‐Based Stack Structure |
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| Authors: | Ping Wei Jiong Yang Liang Guo Shanyu Wang Lihua Wu Xianfan Xu Wenyu Zhao Qingjie Zhang Wenqing Zhang Mildred S. Dresselhaus Jihui Yang |
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| Affiliation: | 1. Materials Science and Engineering Department, University of Washington, Seattle, WA, USA;2. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, P.R. China;3. Materials Genome Institute, Shanghai University, Shanghai, P.R. China;4. School of Mechanical Engineering and BirckNanotechnology Center, Purdue University, West Lafayette, IN, USA;5. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P.R. China;6. Massachusetts Institute of Technology, Cambridge, MA, USA |
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| 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 Bi14Rh3I9 and theoretically predicted for Bi2TeI 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. |
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| Keywords: | lattice dynamics minimum thermal conductivity thermoelectrics topological insulator |
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