Tailoring functionality of perovskite oxide heterostructures using built-in electric field
报告题目:Tailoring functionality of perovskite oxide heterostructures using built-in electric field
报告人:Danyang Wang教授(The University of New South Wales)
Analogous to semiconductors, the built-in electric field in complex oxide thin films and heterostructures also dominates the applications in various devices. It is of both scientific and technical significance to manipulate the strength of the built-in electric field in perovskite oxide thin films for different applications. In this talk, our recent studies on tuning the built-in electric field in ferroelectric multilayers and superlattices by geometric factors will be first discussed. The presence of a built-in electric field was confirmed in aforementioned nanostructures and its strength was highly dependent on the composition gradient direction and superlattice periodicity. The built-in electric field can also be induced through defects, e.g. oxygen vacancies, electronic reconstruction and cation intermixing at the interfaces. Three case studies will be presented in this regard. The first example is the enhancement of piezo-response in Mn doped (Bi, Na)TiO3-BaTiO3thin films through suppressing the oxygen vacancy-induced built-in electric field. Another example is the widely explored oxide twodimensional electron gas (2DEG) LaAlO3/SrTiO3system, in which built-in electric field has been mapped out in the polar LaAlO3layer. Strong oxygen vacancy dependence of magnetic moment and magnetoresistance was found in this non-magnetic heterostructure. The interface charge coupling induced by the cation interdiffusion can also be the key driving force responsible for a giant electrocaloric effect in perovskite bilayer thin films. The excellent tunability of built-in electric field opens an avenue for designing microelectronic and spintronic devices with various functionalities based on perovskite oxide thin films.
Dr Danyang Wang is currently an Australian Research Council Future Fellow (Level 2) andSenior Lecturer in the School of Materials Science and Engineering at UNSW Sydney, ustralia and leading a research group comprising 2 postdoc fellows and 11 postgraduatestudents. He obtained his PhD degree in applied physics from the Hong Kong Polytechnic niversity in December 2006. His research interests cover a broad range of functional aterials, in particular oxide perovskites for nanoelectronic, photonic and energy-harvesting pplications. He has been at the forefront of understanding the processing echniques/conditions that control the materials properties, improving the performance of xisting materials, and exploring new functionalities and their related device applications.