Nanoscale Electromechanics of Paraelectric Materials with Mobile Charges: Size effects and Nonlinearity of Electromechanical Response of SrTiO3 Films

Abstract

Nanoscale enables a broad range of electromechanical coupling mechanisms that are forbidden or negligible in the materials. We conduct a theoretical study of the electromechanical response of thin paraelectric films with mobile vacancies (or ions) paradigmatic for capacitor-type measurements in X-ray scattering, piezoresponse force microscopy (PFM), and electrochemical strain microscopy (ESM). Using quantum paraelectric SrTiO3 film as a model material with well known electromechanical, electronic and electrochemical properties, we evaluate the contributions of electrostriction, Maxwell stress, flexoelectric effect, deformation potential and compositional Vegard strains caused by mobile vacancies (or ions) and electrons to the electromechanical response. The local electromechanical response manifests strong size effects, the scale of which is determined by the ratio of the SrTiO3 film thickness and PFM/ESM tip size to the carriers screening radius. Due to the strong dielectric nonlinearity effect inherent in quantum paraelectrics, the dependence of the SrTiO3 film electromechanical response on applied voltage demonstrates a pronounced crossover from the linear to the quadratic law and then to the sub-linear law with a factor of 2/3 under the voltage increase. The temperature dependence of the electromechanical response as determined by the interplay between the dielectric susceptibility and the screening radius is non-monotonic and has a pronounced maxima, the position and width of which can be tuned by film thickness. This study provides a comparative framework for analysis of electromechanical coupling in the non-piezoelectric nanosystems.

50 pages, 10 figures, 3 appendices, to be submitted to Phys. Rev. B

References in corpus (11)

• Strain gradient induced polarization in SrTiO3 single crystals
• Suppression of Octahedral Tilts and Associated Changes of Electronic Properties at Epitaxial Oxide Heterostructure Interfaces
• Quantum Flexoelectricity in Low Dimensional Systems
• Atomic-scale compensation phenomena at polar interfaces
• Thermodynamics of Electromechanically-Coupled Mixed Ionic-Electronic Conductors: Deformation potential, Vegard strains and Flexoelectric effect
• Electromechanical Detection in Scanning Probe Microscopy: Tip Models and Materials Contrast
• Room temperature surface piezoelectricity in SrTiO3 ceramics via piezoresponse force microscopy
• Piezoresponse Force Spectroscopy of Ferroelectric Materials
• Materials Contrast in Piezoresponse Force Microscopy
• The Piezoresponse Force Microscopy of surface layers and thin films: effective response and resolution function
• Extrinsic Size Effect in Piezoresponse Force Microscopy of Thin Films

Cited by in corpus (17)

• Domain wall conduction in multiaxial ferroelectrics
• Pressure induced switching in ferroelectrics: on the junction between physics and electrochemistry
• Electrostrictive and electrostatic responses in contact mode voltage modulated Scanning Probe Microscopies
• Interface superconductivity in LaAlO${}_3$-SrTiO${}_3$ heterostructures
• Flexocoupling impact on the size effects of piezo- response and conductance in mixed-type ferroelectrics-semiconductors under applied pressure
• Flexocoupling impact on the generalized susceptibility and soft phonon modes in the ordered phase of ferroics
• Frequency Dependent Dynamical Electromechanical Response of Mixed Ionic-Electronic Conductors
• Defect thermodynamics and kinetics in thin strained ferroelectric films: the interplay of possible mechanisms
• Electrochemical Strain Microscopy with Blocking Electrodes: The Role of Electromigration and Diffusion
• Flexo-induced ferroelectricity in low dimensional transition metal dichalcogenides
• Conductivity and thermoelectric coefficients of doped SrTiO${}_3$ at high temperatures
• Conductance switching at the nanoscale of diarylethene derivatives self-assembled monolayers on La${}_{0.7}$Sr${}_{0.3}$MnO${}_3$
• "Forbidden" polarisation and extraordinary piezoelectric effect in organometallic lead halide perovskites
• Mesoscopic mechanism of the domain wall interaction with elastic defects in ferroelectrics
• Hidden Symmetry of Flexoelectric Coupling
• Nanoscale electrical measurements in liquids using AFM - progress and outlook
• Mechanical force involved multiple fields switching of both local ferroelectric and magnetic domain in a Bi5Ti3FeO15 thin film