Flexoelectric induced crack deflection in PbTiO3/SrTiO3 superlattices

The non-trivial topological domains in ferroelectric/dielectric superlattices make them promising for next-generation memory and neuromorphic devices. However, their constituent ferroelectric materials are often inherently brittle, making them susceptible to fracture under external loads. The giant strain gradients near the crack tip can induce significant flexoelectric effects and influence the fracture behavior. This study develops a phase-field model of brittle fracture for PbTiO3/SrTiO3 superlattices. Our model investigates both the evolution of polarization and the propagation of cracks. The calculation results demonstrate that the flexoelectric effect causes crack deflection when cracks propagate through a vortex domain. The direction of this deflection correlates directly with the eigenstrain generated by the flexoelectric effect. Simultaneously, the flexoelectric effect is shown to accelerate the crack propagation rate. This work provides a crucial theoretical basis for evaluating the structural safety and lifespan of ferroelectric superlattice devices.