Flexoelectricity induced increase of critical thickness in epitaxial ferroelectric thin films

Abstract

Flexoelectricity describes the coupling between polarization and strain/stress gradients in insulating crystals. In this paper, using the Landau-Ginsburg-Devonshire phenomenological approach, we found that flexoelectricity could increase the theoretical critical thickness in epitaxial BaTiO3 thin films, below which the switchable spontaneous polarization vanishes. This increase is remarkable in tensile films while trivial in compressive films due to the electrostriction caused decrease of potential barrier, which can be easily destroyed by the flexoelectricity, between the ferroelectric state and the paraelectric state in tensile films. In addition, the films are still in a uni-polar state even below the critical thickness due to the flexoelectric effect.

20 pages, 7 figures

References in corpus (4)

• Strain gradient induced polarization in SrTiO3 single crystals
• Giant Flexoelectric Effect in Ferroelectric Epitaxial Thin Films
• Towards a bulk theory of flexoelectricity
• First-principles theory of frozen-ion flexoelectricity

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• Flexocoupling impact on the generalized susceptibility and soft phonon modes in the ordered phase of ferroics
• Analytical method to determine flexoelectric coupling coefficient at nanoscale
• Hidden Symmetry of Flexoelectric Coupling
• Control of domain states in rhombohedral PZT films via misfit strains and surface charges