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MM: Fachverband Metall- und Materialphysik

MM 59: Computational Materials Modelling IX - Ferroelectrics

MM 59.2: Vortrag

Donnerstag, 3. April 2014, 16:00–16:15, IFW D

Microscopic description of BaTiO₃ and related materials near the ferroelectric phase transition — •Giovanni Pizzi¹, Andrea Cepellotti¹, Samed Halilov², Boris Kozinsky³, Marco Fornari⁴, and Nicola Marzari¹ — ¹Theory and Simulation of Materials, EPFL (CH) — ²Department of Materials Science and Engineering, MIT (USA) — ³Robert Bosch LCC Research and Technology Center, Cambridge (USA) — ⁴Dept. of Physics, Central Michigan University (USA)

Ferroelectric materials like BaTiO₃ have been used for decades in a broad range of technological applications (capacitors, gate dielectrics, IR detectors, holographic memories, …). However, there is still significant debate in the literature concerning the microscopic behavior of these materials, in particular near the paraelectric–ferroelectric phase transition. In BaTiO₃, Ti displacements with respect to the center of the oxygen cage create local dipole moments that are at the origin of the finite polarization in the ferroelectric states. However, these perovskites display a complex energy landscape with multiple local minima. As a result, local finite dipoles exist even in the paraelectric cubic phase, contrary to what is often assumed in simulations. In order to clarify the microscopic behavior of these materials, we perform total-energy calculations to systematically and automatically explore their energy landscape, together with ab-initio molecular dynamics calculations to assess the driving mechanisms for the formation of the different phases and to understand the differences among different structurally similar materials.