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.
While GRIP focuses on the experimental study of giant electro-optic response and optical nonlinearity in 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), results can play a key role in generalizing giant response, leading to the possibility of actually pre-designing highly functional materials. To evaluate the innovation associated to the GRIP proposal, we can identify the following possible outcomes
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.
Possible Outcome O.I) and its innovative impact is based on the phenomenological analogy with
-giant electro-strictive response (see, for example, K. S. Lam et al. Journal of Applied Physics 97, 104112 (2005));
-giant magnetoresistance (see, for example, H. Li et al. Scientific Reports 2, 750 (2012) ).
This analogy suggests that the disorder-driven physics that could be the origin of giant electro-optic response in ferroelectric perovskites could be a general mechanism.
Possible Outcome O.II) has an innovative impact in the context of ever renewed interest in negative statistical temperature physics, these including
-negative absolute temperature statistics in ultra-cold atoms (A. Rapp et al., Physical Review Letters 105, 220405 (2010));
-negative absolute temperature statistics for vibrational motion (S. Braun et al. Science 339, 52-55 (2013)).
Shifted-temperature effects can further help explain other phenomena associated to abnormally reduced thermal fluctuations in transport phenomena.
Possible Outcome O.III) can allow the synthesis of highly functional materials for applications in innovative highly robust memories, for super-efficient electro-optic devices for light modulation and spatial-light-modulation for image projectors.
In terms of dielectric perovskites, the goals and objectives of the GRIP proposal can shed new light into the vast field relaxor ferroelectrics (G.A. Samara, Journal of Physics: Condensed Matter 15, R367-R411 (2003); A. Bokov, Journal of Material Science 41, 31 (2006); A. Bokov and Z. G. Ye Journal of Advances in Dielectrics 2, 1241010 (2012)).