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Invited Lecture

Probing the Structure and Dynamic Behaviors of Ferroelectrics by Electron Microscopy with Atomic Resolution in Real Time

Wednesday (07.06.2017)
17:40 - 18:20 Förde II + III
Part of:
Line-Up:
12:20 Invited Lecture Similarities and differences between magnetic hysteresis and hysteresis in phase transformations 0 Richard James
13:00 Invited Lecture Discovery and Design of Multifunctional Materials using Combinatorial and High-Throughput Experimentation 1 Prof. Dr. Alfred Ludwig
15:10 Invited Lecture Tuning Mechanical Properties of Spider Cuticle by its Composition and by Structural Gradients 0 Dr. Yael Politi
15:50 Invited Lecture Surfaces and Gels for controlling Calcium Phosphate Deposition 0 Prof. Dr. Andreas Taubert
17:40 Invited Lecture Probing the Structure and Dynamic Behaviors of Ferroelectrics by Electron Microscopy with Atomic Resolution in Real Time 0 Prof. Xiaoqing Pan
18:20 Invited Lecture Magnetoelectric Composites for Energy Harvesting 1 Robert E. Hord, Jr. Professor Shashank Priya
19:40 Invited Lecture Declamping in Lead Magnesium Niobate – Lead Titanate Films 1 Prof. Susan Trolier-McKinstry
20:20 Invited Lecture Integrated Magnetics and Multiferroics for Compact and Power Efficient Sensing, Power, RF, Microwave and mm-Wave Electronics 0 Prof. Nian X. Sun
21:00 Invited Lecture From Maxwell’s displacement current to nanogenerator driven self-powered systems and blue energy 0 Prof. Zhong Lin Wang
21:40 Invited Lecture Magnetoelectric Composites: from Sensors to Sensor Systems 0 Prof. Dr.-Ing. Gerhard Schmidt
22:20 Invited Lecture Metal–insulator transition in vanadium oxides films and its applications 1 Dr. Keisuke Shibuya
00:20 Invited Lecture In operando photoemission spectroscopy of PMN-PT interfaces 0 Prof. Dr. Kai Rossnagel
08:30 Invited Lecture Titanium-Tantalum High Temperature Shape Memory Spring Actuators 1 Prof. Dr. Gunther Eggeler
09:10 Invited Lecture Vortex-antivortex topological structures in multiferroic tunnel junctions 1 Dr. Ana Sanchez
09:50 Invited Lecture Artificial Ferroic Systems 1 Prof. Laura Heyderman
17:40 Invited Lecture Biomimicry at the molecular level: Molecularly imprinted polymers as synthetic antibody mimics 0 Karsten Haupt
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Ferroelectric materials have been utilized in a broad range of electronic, optical, and electromechanical applications and hold promise for the design of high-density nonvolatile memories and multifunctional nano-devices. The applications of ferroelectric materials stem from the ordering of polarization and switching of the polarization states by applied bias. A fundamental understanding of the atomic scale mechanism underlying the domain formation and polarization switching, therefore, is critical for the design of devices.  In this work, I will present the emergent properties of polarization ordering and domain switching in multiferroic BiFeO3 thin films, uncovered by in situ atomic resolution transmission electron microscopy (TEM).  We found that the charged domain walls can be created or erased by applying a bias, and the resistance of the local film strongly depends on the characteristics of these charged domain walls.  Furthermore, by mapping the polarization distribution, we found that a monolayer thick conducting oxide existing on the BiFeO3 film surface causes a significant increase of local polarization and exotic high-density nano-domains with large strain variations emerge. Finally, I will show that small defects in ferroelectric thin films can act as nano-building-blocks for the emergence of novel topological states of polarization ordering, namely, hedgehog/antihedgehog nanodomain arrays in BiFeO3.  The emergent polarization states such as hedgehog/antihedgehog and vortex/ antivortex topologies not only modify the local lattice symmetries and thus induce the coexistence of mixed-phases resembling the morphotropic phase boundary with high piezoelectricity, but also lead to flux-closure vortex structures.  Phase-field simulations suggest that the observed novel polarization states are formed due to the coupling between the polarization ordering and the charged defects existing in the films. Thus, engineering of defects may provide a new route for developing ferroelectic/multiferroic-based nanodevices.

 

Speaker:
Prof. Xiaoqing Pan
University of California, Irvine