Out-of-equilibrium study of ferroelectric switching in lead free perovskites with near-room temperature instabilities.

The experiment will focus on the ultrafast photo-induced dynamics in ferroelectric thin films of KTN (K(Nb1-xTax)O3 following in particular the dynamics of strain and symmetry change. We will compare textured thin film grown on 2 different substrates (R-cut sapphire and MgO) with the same composition of KTN x=0.65. This composition is chosen for having the para/ferrolectic transition close to room temperature. This will allow us to study the ultrafast dynamics in the 4 structural phases (with different symmetry and ferroelectic order) and is of interest for future applications. We expect to determine the dynamics of the structural phase transition after ultrafast optical excitation, identify the bottlenecks in the commutation of the ferroelectic order and understand the key parameters influencing the relaxation.