Predicting Novel 2D MB2 (M = Ti, Hf, V, Nb, Ta) Monolayers with Ultrafast Dirac Transport Channel and Electron-Orbital Controlled Negative Poisson's Ratio

Chunmei Zhang; Tianwei He; Sri Kasi Matta; Ting Liao; Liangzhi Kou; Zhongfang Chen; Aijun Du

doi:10.1021/acs.jpclett.9b00762

Predicting Novel 2D MB₂ (M = Ti, Hf, V, Nb, Ta) Monolayers with Ultrafast Dirac Transport Channel and Electron-Orbital Controlled Negative Poisson's Ratio

J Phys Chem Lett. 2019 May 16;10(10):2567-2573. doi: 10.1021/acs.jpclett.9b00762. Epub 2019 May 6.

Authors

Chunmei Zhang¹, Tianwei He¹, Sri Kasi Matta¹, Ting Liao¹, Liangzhi Kou¹, Zhongfang Chen², Aijun Du¹

Affiliations

¹ School of Chemistry, Physics and Mechanical Engineering , Queensland University of Technology , Gardens Point Campus, Brisbane , Queensland 4001 , Australia.
² Department of Chemistry , University of Puerto Rico , Rio Piedras Campus, San Juan , Puerto Rico 00931 , United States.

PMID: 31046284
DOI: 10.1021/acs.jpclett.9b00762

Abstract

Three-dimensional diborides MB₂, featured in stacking the M layer above the middle of the honeycomb boron layer, have been extensively studied. However, little information on the two-dimensional counterparts of MB₂ is available. Here, by means of evolutionary algorithm and first-principles calculations, we extensively studied the monolayer MB₂ crystal with M elements ranging from group IIA to IVA covering 34 candidates. Our computations screened out eight stable monolayers MB₂ (M = Be, Mg, Fe, Ti, Hf, V, Nb, Ta), and they exhibit Dirac-like band structures. Dramatically, among them, groups IVB-VB transition-metal diboride MB₂ (M = Ti, Hf, V, Nb, Ta) are predicted to be a new class of auxetic materials. They harbor in-plane negative Poisson's ratio (NPR) arising mainly from the orbital hybridization between M d and Boron p orbitals, which is distinct from previously reported auxetic materials. The unusual NPR and the Dirac transport channel of these materials are applicable to nanoelectronics and nanomechanics.