The Outstanding Young Investigator Award has been established to recognize outstanding interdisciplinary materials research by a young scientist or engineer. This award is presented to Harold Y. Hwang of the University of Tokyo, for his innovative work on the materials physics of transition metal oxides and the atomic-scale synthesis of complex oxide heterostructures. (We invite you to find out more about the Outstanding Young Investigator award.)

Harold Y. Hwang University of Tokyo (view biography) Presentation: Atomic Control of the Electronic Structure at Complex Oxide Heterointerfaces (view abstract) Tuesday, March 29 5:05 p.m. Room 2010/2012 Moscone West

Harold Y. Hwang Biography

Harold Y. Hwang received a BS in physics, a BS and MS in electrical engineering from the Massachusetts Institute of Technology (1993), and a PhD in physics from Princeton University (1997). In 1996, he joined Bell Laboratories, Lucent Technologies as a member of the technical staff in the Materials Physics Research Department. He joined the University of Tokyo in 2003 as an associate professor in the Departments of Advanced Materials Science and Applied Physics. Hwang has been active in the study of charge transport, spin and lattice dynamics, and ordering transitions in transition metal oxides, as well as in the development of chalcogenide glass waveguides and claddings for photonics applications. His current research interests are on the atomic-scale synthesis of thin-film complex oxide heterostructures, focusing on the control of the electronic structure at interfaces and in confined geometries. Hwang has received a Sakigake Fellowship from the Japan Science and Technology Agency (2003) and a Mitsubishi Foundation Award (2004).

Atomic Control of the Electronic Structure
at Complex Oxide Heterointerfaces

Perovskite oxides exhibit an incredibly broad range of physical properties, from insulators to superconductors, incorporating magnetism, and coupling to phonon instabilities. The close lattice match between many perovskites raises the possibility of growing epitaxial thin-film heterostructures with different ground states which may compete or interact. Recent development of superconducting Josephson junctions, magnetic-tunnel junctions, ferroelectric memory cells, resistive switching, etc., can be considered as examples within this new heteroepitaxial family. In this context, we present our studies of the electronic structure at atomically abrupt interfaces grown by pulsed-laser deposition. Some issues are generic to all heterointerfaces, such as the stability of dopant profiles and diffusion, interface states and depletion, and interface charge arising from polarity discontinuities. An unusual aspect of these materials is the large lattice polarization at interfaces, which can dramatically extend charge-screening lengths. Another more unique issue is the charge structure associated with Mott-insulator/band-insulator interfaces. The question is: how should one consider the correlated equivalent of band bending? This semiconductor concept is based on the validity of rigid single-particle band diagrams, which are known to be an inadequate description for strongly correlated electrons. In addition to presenting an interesting scientific challenge, this underlies attempts to develop new applications of doped Mott insulators in device geometries.