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Adv Mater. 2019 Feb;31(7):e1804979. doi: 10.1002/adma.201804979. Epub 2018 Dec 27.

In-Plane Anisotropic Thermal Conductivity of Few-Layered Transition Metal Dichalcogenide Td-WTe2.

Author information

1
Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), Xi'an, 710129, China.
2
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
3
Key Laboratory of Micro and Nano Photonic Structures (MOE), Department of Optical Science and Engineering, Fudan University, Shanghai, 200433, China.
4
State Key Laboratory of ASIC and System, School of Information Science and Technology, Fudan University, Shanghai, 200433, China.
5
Key Laboratory of RF Circuits and System of Ministry of Education, Hangzhou Dianzi University, Hangzhou, 310018, China.
6
School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
7
Key Laboratory of Chemical Lasers, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
8
Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.
9
Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211800, China.

Abstract

2D Td-WTe2 has attracted increasing attention due to its promising applications in spintronic, field-effect chiral, and high-efficiency thermoelectric devices. It is known that thermal conductivity plays a crucial role in condensed matter devices, especially in 2D systems where phonons, electrons, and magnons are highly confined and coupled. This work reports the first experimental evidence of in-plane anisotropic thermal conductivities in suspended Td-WTe2 samples of different thicknesses, and is also the first demonstration of such anisotropy in 2D transition metal dichalcogenides. The results reveal an obvious anisotropy in the thermal conductivities between the zigzag and armchair axes. The theoretical calculation implies that the in-plane anisotropy is attributed to the different mean free paths along the two orientations. As thickness decreases, the phonon-boundary scattering increases faster along the armchair direction, resulting in stronger anisotropy. The findings here are crucial for developing efficient thermal management schemes when engineering thermal-related applications of a 2D system.

KEYWORDS:

2D transition-metal dichalcogenides; in-plane anisotropy; mean free paths; suspended Td-WTe2; thermal conductivity

PMID:
30589108
DOI:
10.1002/adma.201804979

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