Understanding and controlling dipolar Moiré pattern in ferroelectric perovskite oxide nanolayers

Twisted atomic bilayers of ferroelectrics show unprecedented moir\'e patterns hosting interpenetrating arrays of dipolar vortices and antivortices. Monte Carlo simulations confirm the critical role of the flexoelectric coupling in mediating the emergence of these polar nanotextures in response to the shear strain gradient created by the twisting angle. The authors reveal here that these polar nano-objects, of high relevance to ultra-dense memory and computing applications, can be manipulated by electric fields, in a manner reminiscent of the Berezinskii-Kosterlitz-Thouless phase transition.