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Probing Emergent Phenomena in Complex Oxides through Nonlinear Optics and Coherent X-rays

Date and Time: Tuesday, October 13, 2020, 01:30pm -
Location: Zoom

Speaker: Venkatraman Gopalan (Department of Materials Science and Engineering, and Department of Physics, Pennsylvania State University)

The fast-paced improvements in ultrafast radiation from X-ray, ultraviolet, visible, and infrared to terahertz frequencies is enabling simultaneous probing of electron, phonon, and spin dynamics on the ps-to-ns time scales, as well as sub-micrometer length scales. In this talk, I will present brief introduction to nonlinear optics, followed by examples of the discovery of new low symmetry phases with large property enhancements in decades old ferroelectric crystals using nonlinear optical microscopy. In a second example, I will show how an ultrafast laser pulse can create a complex polar supercrystal with a giant unit cell of tens of nanometers in each dimension. Finally, I will present an example of a phase-reconstruction technique using X-ray by which a complete three-dimensional electron density is reconstructed on the atomic scale in an epitaxial film of a low symmetry complex oxide on a substrate.

Brief Bio: Gopalan received his PhD in Materials science and Engineering at Cornell University in 1995. After a brief stint as a postdoctoral scholar in the electrical and Computer Engineering at the Carnegie Mellon University, he joined Los Alamos National Labs as Director-funded Postodctoral fellow. In 1999, he joined Pennsylvania State University as a tenure-track assistant professor, and became a full professor in 2008. His interests are in symmetry, quantum materials, nonlinear optical imaging and spectroscopy, diffraction techniques, and optical device applications. He is the recipient of the NSF Career award, Robert R. Coble award and Richard M. Fulrath award both from the American Ceramics Society, and the Faculty Scholar Medal from the Pennsylvania State University. He is a Fellow of the American Physical Society.

Host:  Sang-Wook Cheong

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