Strain-engineered divergent electrostriction in KTaO3

We investigate the electrostrictive response across a ferroelectric phase transition from first-principles calcu- lations and show that M, the field-induced electrostrictive tensor, controlling the amplitude of the electric-field induced strain, can be made arbitrarily large through strain engineering. We take as a case study the epitaxial strain-induced transition from para- to ferroelectricity of KTaO3 . We show that the magnitude of the field-induced electrostriction diverges with the permittivity at the transition, hence exhibiting giant responses through a calcu- lation of both the M and Q electrostrictive tensors. We explain the origin of this giant electrostrictive response in KTaO3 using a microscopic decomposition of the electrostriction coefficients, and use this understanding to propose design rules for the development of future giant electrostrictors for electromechanical applications. Finally, we introduce a further means to calculate electrostriction, specific to ferroelectrics, and not yet utilized in the literature.