Enhanced flexoelectricity at reduced dimensions revealed by mechanically tunable quantum tunnelling

Abstract

Flexoelectricity is a universal electromechanical coupling effect whereby all dielectric materials polarize in response to strain gradients. In particular, nanoscale flexoelectricity promises exotic phenomena and functions, but reliable characterization methods are required to unlock its potential. Here, we report anomalous mechanical control of quantum tunnelling that allows for characterizing nanoscale flexoelectricity. By applying strain gradients with an atomic force microscope tip, we systematically polarize an ultrathin film of otherwise nonpolar SrTiO${}_3$, and simultaneously measure tunnel current across it. The measured tunnel current exhibits critical behaviour as a function of strain gradients, which manifests large modification of tunnel barrier profiles via flexoelectricity. Further analysis of this critical behaviour reveals significantly enhanced flexocoupling strength in ultrathin SrTiO${}_3$, compared to that in bulk, rendering flexoelectricity more potent at the nanoscale. Our study not only suggests possible applications exploiting dynamic mechanical control of quantum effect, but also paves the way to characterize nanoscale flexoelectricity.

arXiv commentMain and Supplementary combined, 40 pages

References in corpus (12)

• Phonons and related properties of extended systems from density-functional perturbation theory
• Giant Electroresistance in Ferroelectric Tunnel Junctions
• Strain gradient induced polarization in SrTiO3 single crystals
• Tunneling electroresistance effect in ferroelectric tunnel junctions at the nanoscale
• Giant Flexoelectric Effect in Ferroelectric Epitaxial Thin Films
• Theoretical current-voltage characteristics of ferroelectric tunnel junctions
• Ab initio calculations of the atomic and electronic structure of CaTiO3 (001) and (011) surfaces
• Controlled manipulation of oxygen vacancies using nanoscale flexoelectricity
• Surface control of flexoelectricity
• Growth control of oxygen stoichiometry in homoepitaxial SrTiO3 films by pulsed laser epitaxy in high vacuum
• Characterization of the Schottky Barrier in SrRuO3/Nb:SrTiO3 Junctions
• Modifying the surface electronic properties of YBa2Cu3O7-delta with cryogenic scanning probe microscopy

Cited by in corpus (8)

• Does Flexoelectricity Drive Triboelectricity?
• Giant strain gradient elasticity in SrTiO3 membranes: bending versus stretching
• Ultrahigh flexoelectric effect of 3D interconnected porous polymers: modelling and verification
• Flexoelectric control of a ferromagnetic metal
• Achieving ferroelectricity in a centrosymmetric high-performance semiconductor by strain engineering
• Large spin-Hall effect in Si at room temperature
• High-strain-induced local modification of the electronic properties of VO${}_2$ thin films
• Flexoelectronic doping of the degenerate silicon and the correlated electron behavior