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Nondestructive picosecond ultrasonic probing of intralayer and van der Waals interlayer bonding in α- and β-In2Se3

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posted on 05.10.2021, 11:07 by Wenjing Yan, Andrey Akimov, Joe Page, Mark GreenawayMark Greenaway, Alexander BalanovAlexander Balanov, Amalia Patane, Anthony Kent
The interplay between the strong intralayer covalent-ionic bonds and the weak interlayer van der Waals (vdW) forces between the neighboring layers of vdW crystals give rise to unique physical and chemical properties. Here, we study the intralayer and interlayer bonding in α and β polytypes of In2Se3, a vdW material with potential applications in advanced electronic and optical devices. We conduct picosecond ultrasonic experiments to probe the sound velocity in the direction perpendicular to the vdW layers. The measured sound velocities are different in α- and β-In2Se3, suggesting a significant difference in their elastic properties. We use density functional theory and an effective spring model to calculate the elastic stiffness of the layer and vdW gap in α- and β-In2Se3. The calculated elastic moduli show good agreement with experimental values and reveal the dominant contribution of interlayer atomic bonding to the different elastic properties of the two polytypes. Our findings show the power of picosecond ultrasonics for probing the fundamental elastic properties of vdW materials; also, our data and analysis provide a reliable description of the intra- and inter-layer forces in complex crystal structures, such as the polytype phases of In2Se3.

Funding

Quantum dynamics of electrons in emerging van der Waals devices

Engineering and Physical Sciences Research Council

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Designing and exploring new quantum materials based on Fermi surface topological transitions

Engineering and Physical Sciences Research Council

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European Union’s Horizon 2020 research and innovation program under grant agreement Graphene Core 3

Anne McLaren Research fellowship

History

School

  • Science

Department

  • Physics

Published in

Advanced Functional Materials

Volume

31

Issue

50

Publisher

Wiley

Version

VoR (Version of Record)

Rights holder

© The Authors

Publisher statement

This is an Open Access Article. It is published by Wiley under the Creative Commons Attribution 4.0 International Licence (CC BY 4.0). Full details of this licence are available at: https://creativecommons.org/licenses/by/4.0/

Acceptance date

23/08/2021

Publication date

2021-09-09

Copyright date

2021

ISSN

1616-301X

eISSN

1616-3028

Language

en

Depositor

Dr Alexander Balanov. Deposit date: 24 August 2021

Article number

2106206