Ultralow-frequency collective compression mode and strong interlayer coupling in multilayer black phosphorus

Abstract

The recent renaissance of black phosphorus (BP) as a two-dimensional 2D layered material has generated tremendous interest in its tunable electronic band gap and highly anisotropic transport properties that offer new opportunities for device applications. Many of these outstanding properties are attributed to its unique structural characters that still need elucidation. Here we show Raman measurements that reveal an ultralow-frequency collective compression mode (CCM), which is unprecedented among similar 2D layered materials. This novel CCM indicates an unusually strong interlayer coupling in BP, which is quantitatively supported by a phonon frequency analysis and first-principles calculations. Moreover, the CCM and another branch of low-frequency Raman modes shift sensitively with changing number of layers, allowing an accurate determination of the thickness up to tens of atomic layers, which is considerably higher than those previously achieved by using high-frequency Raman modes. These results offer fundamental insights and practical tools for exploring multilayer BP in new device applications.

19 pages, 4 figures, 1 table, 30 references, supplementary information included

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Cited by in corpus (9)

• Black phosphorus: narrow gap, wide applications
• Stacking-Dependent Interlayer Phonons in 3R and 2H MoS${}_2$
• Interlayer bond polarizability model for stacking-dependent low-frequency Raman scattering in layered materials
• Shear and breathing modes of layered materials
• Second-Order Raman Scattering in Exfoliated Black Phosphorus
• Anisotropic Charge Carrier and Coherent Acoustic Phonon Dynamics of Black Phosphorus Studied by Transient Absorption Microscopy
• Ultrafast carrier-coupled interlayer contraction, coherent intralayer motions, and phonon thermalization dynamics of black phosphorus
• Cross-Examination of Photoinitiated Carrier and Structural Dynamics of Black Phosphorus at Elevated Fluences
• Straightforward Method to Orient Black Phosphorus from Bulk to Thin Layers using a Standard Green Laser