Piezoelectricity and valley chern number in inhomogeneous hexagonal 2D crystals

Rostami, HabibStockholms universitet,Nordiska institutet för teoretisk fysik (Nordita),Istituto Italiano di Tecnologia, Graphene Labs, Italia,Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy, Stockholm Univ, SE-10691 Stockholm, Sweden.;Nordita SU (author)

QC 20200316
Conversion of mechanical forces to electric signal is possible in non-centrosymmetric materials due to linear piezoelectricity. The extraordinary mechanical properties of two-dimensional materials and their high crystallinity make them exceptional platforms to study and exploit the piezoelectric effect. Here, the piezoelectric response of non-centrosymmetric hexagonal two-dimensional crystals is studied using the modern theory of polarization and k-p model Hamiltonians. An analytical expression for the piezoelectric constant is obtained in terms of topological quantities, such as the valley Chern number. The theory is applied to semiconducting transition metal dichalcogenides and hexagonal Boron Nitride. We find good agreement with available experimental measurements for MoS2. We further generalize the theory to study the polarization of samples subjected to inhomogeneous strain (e.g., nanobubbles). We obtain a simple expression in terms of the strain tensor, and show that charge densities greater than or similar to 10(11)cm(-2) can be induced by realistic inhomogeneous strains, epsilon approximate to 0.01-0.03.

Guinea, FranciscoFdn IMDEA Nanociencia, C Faraday 9,Campus Cantoblanco, Madrid 28049, Spain.;Univ Manchester, Sch Phys & Astron, Oxford Rd, Manchester M13 9PL, Lancs, England. (author)
Polini, MarcoIst Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy.;Univ Manchester, Sch Phys & Astron, Oxford Rd, Manchester M13 9PL, Lancs, England. (author)
Roldan, RafaelCSIC, ICMM, Mat Sci Factory, E-28049 Madrid, Spain. (author)
Stockholms universitetNordiska institutet för teoretisk fysik (Nordita) (creator_code:org_t)

By the author/editor: Rostami, Habib; Guinea, Francisc ...; Polini, Marco; Roldan, Rafael

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