Competing polarization reversal mechanisms in ferroelectric nanowires

Polarization reversal in ferroelectrics has been a subject of intense interest for many years owing to both its scientific appeal and practical utility. In recent years the interest has increased even further thanks to the expectations of achieving ultrafast polarization reversal at the nanoscale. While most of the studies up to now are focused on the polarization reversal in ferroelectric thin films, we report the intrinsic dynamics of ultrafast polarization reversal in ferroelectric nanowires. Using atomistic first-principles-based simulations, we trace the time evolution of polarization under applied electric field to reveal the existence of two competing polarization reversal mechanisms: (i) domain-driven and (ii) homogeneous. The analysis of their microscopic origin allows us to postulate the associated laws and leads to a deeper understanding of polarization reversal dynamics in general. In addition, we find that in defect-free nanowires the polarization reversal can occur within picoseconds, which potentially is very promising for ultrafast memory and other applications.