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Departmental Colloquium

Functional Oxide Materials Discovery by Epitaxial Design  
Guest Speaker
Dr. Ho Nyung Lee  
Guest Affiliation
Oak Ridge National Laboratory  
Thursday, October 15, 2015 3:30 pm - 4:30 pm  
Physics Auditorium (Rm. 202)  

Complex oxides are known to possess the full spectrum of fascinating properties, including magnetism, colossal magneto-resistance, superconductivity, ferroelectricity, pyroelectricity, piezoelectricity, multiferroicity, ionic conductivity, and more. This breadth of remarkable properties is the consequence of strong coupling between charge, spin, orbital, and lattice symmetry. Spurred by recent advances in the synthesis of such artificial materials at the atomic scale, the physics of oxide heterostructures containing atomically smooth layers of such correlated electron materials with abrupt interfaces is a rapidly growing area. Thus, we have established a growth technique to control complex oxides at the level of unit cell thickness by pulsed laser epitaxy. The atomic-scale growth control enables to assemble the building blocks to a functional system in a programmable manner, yielding many intriguing physical properties that cannot be found in bulk counterparts. In this talk, examples of artificially designed, functional oxide heterostructures will be presented, highlighting the importance of heterostructuring, interfacing, and straining.

The main topics include (1) fast, reversible redox reactions in epitaxial 'SrCoOx oxygen sponges' and their strain control for improved catalytic oxygen reduction reaction, (2) understanding oxygen vacancy stability in layered oxides: brownmillerite and Ruddlesden-Popper oxides, (3) orbital polarization in LaNiO3 thin films for improved oxygen catalysis, (4) improving carrier transport and thermoelectric power of oxide 2D electron gases in LaTiO3/SrTiO3 superlattices by fractional delta doping, and (5) spin-orbit coupling in SrIrO3 thin films and heterostructures.