Wei, Bin; Liu, Junyan; Cai, Qingan; Alatas, Ahmet; Said, Ayman H.; Hua, Meihua; ChenLi,; Hong, Jiawang
Giant anisotropic in-plane thermal conduction induced by Anomalous phonons in pentagonal PdSe2 Journal Article
In: Materials Today Physics, vol. 22, no. 100599, 2022.
Abstract | Links | BibTeX | Tags: anharmonicity, TMD
@article{nokey,
title = {Giant anisotropic in-plane thermal conduction induced by Anomalous phonons in pentagonal PdSe2},
author = {Bin Wei and Junyan Liu and Qingan Cai and Ahmet Alatas and Ayman H. Said and Meihua Hua and ChenLi and Jiawang Hong},
url = {https://www.sciencedirect.com/science/article/pii/S2542529321002601?dgcid=coauthor},
doi = {10.1016/j.mtphys.2021.100599},
year = {2022},
date = {2022-01-01},
urldate = {2021-12-23},
journal = {Materials Today Physics},
volume = {22},
number = {100599},
abstract = {In two-dimensional materials, different atomic stacking induces anisotropic atomic interactions and phonon dispersions, leading to the anisotropy of in-plane thermal transport. Here, we report an exceptional case in layered pentagonal PdSe2, where the bonds, force constants, and lattice constants are nearly-equal along the in-plane crystallographic axis directions, while the thermal conductivity is surprisingly much greater along b-axis than along a-axis with a ratio up to 1.8. Such strong anisotropy is not only unexpected in in-plane uniform structured materials, but also comparable to the record high in-plane anisotropic thermal conductivity in the nonuniform structured material reported to date (the ratio is ∼2.0 in TiS3). By combining the inelastic X-ray scattering measurement and the first-principles calculations, we attribute such high anisotropy to the low-energy phonons along a-axis, particularly their lower group velocities and “avoided-crossing” behavior. The different buckling structures between a- (zigzag-type) and b-axis (flat-type) are mainly responsible for such unique phonon dynamics properties of PdSe2. This finding helps to discover materials with high anisotropic in-plane thermal conductivity in uniform structures and reveals new physics of anisotropy of in-plane thermal conduction. Due to the unique features in structure and thermal transport properties, PdSe2 may serve as a new platform for designing novel devices to route heat flow precisely at the nanoscale.},
keywords = {anharmonicity, TMD},
pubstate = {published},
tppubtype = {article}
}
In two-dimensional materials, different atomic stacking induces anisotropic atomic interactions and phonon dispersions, leading to the anisotropy of in-plane thermal transport. Here, we report an exceptional case in layered pentagonal PdSe2, where the bonds, force constants, and lattice constants are nearly-equal along the in-plane crystallographic axis directions, while the thermal conductivity is surprisingly much greater along b-axis than along a-axis with a ratio up to 1.8. Such strong anisotropy is not only unexpected in in-plane uniform structured materials, but also comparable to the record high in-plane anisotropic thermal conductivity in the nonuniform structured material reported to date (the ratio is ∼2.0 in TiS3). By combining the inelastic X-ray scattering measurement and the first-principles calculations, we attribute such high anisotropy to the low-energy phonons along a-axis, particularly their lower group velocities and “avoided-crossing” behavior. The different buckling structures between a- (zigzag-type) and b-axis (flat-type) are mainly responsible for such unique phonon dynamics properties of PdSe2. This finding helps to discover materials with high anisotropic in-plane thermal conductivity in uniform structures and reveals new physics of anisotropy of in-plane thermal conduction. Due to the unique features in structure and thermal transport properties, PdSe2 may serve as a new platform for designing novel devices to route heat flow precisely at the nanoscale.