Ricerc@Sapienza

The GRIP proposal aims at pooling together groups at La Sapienza carrying out research in photonics, spectroscopy, and solid state physics to investigate the origin of anomalous and giant response discovered in compositionally disordered perovskites. The basic goals of the project are
G.I) establish the role of mesoscopic and nanoscopic clusters in the formation of slim-loop response functions;
G.II) analyze experimentally shifted statistical temperature effects and out-of-equilibrium dynamics through macroscopic response;
G.III) explore the microscopic origin of giant nonlinear response in compositionally disordered perovskite ferroelectrics.
In GRIP, focus is on the experimental study of giant electro-optic response and optical nonlinearity in disordered perovskite ferroelectrics, specifically on solid-solutions of KLTN (potassium-lithium-tantalate-niobate K(1-x)Li(x)Ta(1-y)Nb(y)O(3), x=0.04, y=0.38), and KNTN (potassium-sodium-tantalate-niobate K(1-x)Na(x)Ta(1-y)Nb(y)O3, x=0.15, y=0.37), in addition to the parent KTN (KTaO(3)). These have been the arena of a series of breakthroughs in photonics: i) the breakdown of diffraction limits in optical propagation; ii) the manifestation of giant optical nonlinearity allowing the observation of spatial rogue waves and replica-symmetry-breaking; and iii) the identification of a new ferroelectric metastable phase that forms a sponatenous large-scale super-crystal.
Key expected outcomes of GRIP are:
O.I) the elaboration of a model mechanism leading to giant anomalous response from mesoscopic disorder that can be generalized to describe analogous behavior in other complex solids;
O.II) the demonstration of a general shifted statistical temperature model that can allow the exploration of near-absolute-zero and negative-statistical temperature physics at room temperature;
O.III) the elaboration of new growth, characterization, and preparation protocols to enhance intrinsically nonlinear macroscopic response.