BEGIN:VCALENDAR VERSION:2.0 PRODID:-//SPIP/Plugin Agenda//NONSGML v1.0//FR X-WR-TIMEZONE:Europe/Paris CALSCALE:GREGORIAN X-WR-CALNAME;VALUE=TEXT:Séminaire - Jorge Iñiguez -- Unité Mixte de Physique CNRS/Thales X-WR-RELCALID: BEGIN:VEVENT SUMMARY:Séminaire - Jorge Iñiguez UID:20160126T170657Z-a245-e16@ DTSTAMP:20160126T170657Z DTSTART:20160211T130000Z DTEND:20160211T140000Z CREATED:20160126T170657Z LAST-MODIFIED:20160126T160709Z ORGANIZER;CN=CNRS-Thales[] ATTENDEE:Jorge Iñiguez DESCRIPTION:Over the past few years\, we have come across a large number of intriguing problems featuring novel structural and lattice-dynamical effects in ferroelectric and multiferroic ABO 3 perovskite oxides. A realistic investigation of such problems mandatorily requires : (1) large-scale simulations (e.g.\, to address the multi-domain configurations ubiquitous in ferroics)\, (2) incorporating thermal effects (e.g.\, to investigate temperature-driven transitions and activated phenomena)\, (3) with quantum-like accuracy (as the effects of interest are often controlled by energy differences of a few meV per atom)\, and (4) capable of tackling chemically inhomogeneous situations (ranging from solid solution to short-period super-lattices where interfacial and confinement effects control the properties of interest). In this talk I will present our work to develop first-principles-based lattice-dynamical models that satisfy all these requirements. I will discuss applications (to unveil structural transitions occurring within ferroelectric domains walls\, to explain the origin of a striking negative-capacitance effect in ferroelectric/dielectric superlattices) that illustrate the predictive power of the new models and their ability to go beyond the state of the art. Time allowing\, I will also describe a strategy to incorporate (the relevant) electronic degrees of freedom in the model simulations. I will illustrate the resulting approach with applications to physically non-trivial cases (interface-confined electron gases\, magnetic order in strongly-correlated oxides)\, showing that it allows us to obtain first-principles-like accuracy at a much reduced computational cost. I will conclude by giving an outlook of the challenges and opportunities in the field. Work done in collaboration with many colleagues\, especially : Pablo Garcia-Fernandez and Javier Junquera (U. Cantabria\, Spain) on the development of the scheme that incorporates electrons ; Carlos Escorihuela-Sayalero (Luxembourg Institute of Science and Technology) and Jacek C. Wojdel (Institute de Ciencia de Materials de Barcelona\, Spain) on the lattice-dynamical models. CATEGORIES:Séminaire - Jorge Iñiguez URL: SEQUENCE:0 STATUS:CONFIRMED END:VEVENT END:VCALENDAR