2026-09-17 ペンシルベニア州立大学（Penn State）
＜関連情報＞
- https://www.psu.edu/news/research/story/tiny-wrinkles-bend-physics-change-how-electricity-moves-through-graphene
- https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202518224
- https://journals.aps.org/prb/abstract/10.1103/PhysRevB.77.033403
サブナノメートル曲率がグラフェンにおける量子軌道フレキソ電気効果を解き放つ Sub-Nanometer Curvature Unlocks Quantum Orbital Flexoelectricity in Graphene
Sathvik Ajay Iyengar, James G. McHugh, Jonathan P. Salvage, Robert Vajtai, Venkataramana Gadhamshetty, Alan B. Dalton, Manoj Tripathi, …
Advanced Materials Published: 25 July 2026
DOI:https://doi.org/10.1002/adma.202518224
ABSTRACT
Flexoelectricity, defined as polarization induced by strain gradients, is especially pronounced in two-dimensional (2D) materials due to their mechanical flexibility and sensitivity to deformation. In nanostructures with nanometer-scale curvature, bending can perturb out-of-plane π orbitals and generate quantum-mechanical polarization and electrostatic modulation beyond classical lattice distortion alone. Here, we combine scanning probe measurements and first-principles calculations to provide experimental and theoretical evidence for large intrinsic quantum orbital flexoelectricity in graphene nanowrinkles (GNWrs) with estimated polarization densities of Pth ∼ 4 C m−2 and Pexp ∼ 1 C m−2, exceeding those of mesoscale systems by 5 to 7 orders of magnitude. These GNWrs exhibit high apex curvature, undergo atomic-level buckling, and produce localized strain fields, as supported by atomic force microscopy analysis and Raman spectroscopy. Kelvin probe force microscopy reveals curvature-dependent work-function shifts, while conductive atomic force microscopy detects reproducible GNWr-associated currents with a threshold voltage (Φth ∼ 1 V) comparable to the band offset predicted by ab initio calculations (∼ 1.2 V). These results support an interpretation in which curvature-induced flexoelectric dipoles reshape the local electronic potential. GNWrs therefore provide a structurally simple carbon-based platform for probing quantum-mechanical flexoelectricity.
低次元系における電子フレキソ電気効果 Electronic flexoelectricity in low-dimensional systems
Sergei V. Kalinin and Vincent Meunier
Physical Review B Published: 4 January, 2008
DOI: https://doi.org/10.1103/PhysRevB.77.033403
Abstract
Symmetry breaking at surfaces and interfaces and the capability to support large strain gradients in nanoscale systems enable unusual forms of electromechanical coupling. Here, we introduce the concept of electronic flexoelectricity, a phenomenon that is manifested when the mechanical deformation of nonpolar quantum systems results in the emergence of net dipole moments and hence linear electromechanical coupling proportional to local curvature. The concept is illustrated in carbon systems, including polyacetylene and nanographitic ribbons. Using density functional theory calculations for systems made of up to 400 atoms, we determine the flexoelectric coefficients to be of the order of ∼0.1, in agreement with the prediction of linear theory. The implications of electronic flexoelectricity on electromechanical device applications and physics of carbon-based materials are discussed.
