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Static flexural modes and piezoelectricity in 2D and layered crystals
Author(s) -
Michel Karl H.,
NeekAmal Mehdi,
Peeters Francois M.
Publication year - 2016
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201600226
Subject(s) - anharmonicity , piezoelectricity , condensed matter physics , materials science , flexoelectricity , monolayer , polarization (electrochemistry) , nanoscopic scale , lattice (music) , nanotechnology , chemistry , physics , composite material , acoustics
Piezo‐ and flexoelectricity are manifestations of electromechanical coupling in solids with potential applications in nanoscale materials. Naumov et al. [Phys. Rev. Lett. 102 , 217601 (2009)] have shown by first principles calculations that a monolayer BN sheet becomes macroscopically polarized in‐plane when in a corrugated state. Here, we investigate the interplay of layer corrugation and in‐plane polarization by atomistic lattice dynamics. We treat the coupling between static flexural modes and in‐plane atomic ion displacements as an anharmonic effect, similar to the membrane effect that is at the origin of negative thermal expansion in layered crystals. We have derived analytical expressions for the corrugation‐induced static in‐plane strains and the optical displacements with the resulting polarization response functions. Beyond h‐BN, the theory applies to transition metal dichalcogenides and dioxides. Numerical calculations show that the effects are considerably stronger for 2D h‐BN than for2 H − MoS 2 .