Materials Science Research Lecture

Abstract: Complex oxide materials, which exhibit a wide range of structures and functionalities such as superconductivities, magnetic and multiferroic properties, have driven considerable research in materials science and condensed matter physics over past decades. As one important variant of oxide materials, ferroelectric materials which possess an electrically-addressable polarization hold great promise for next-generation non-volatile, low-power nanoelectronics. Leveraging the polarization and the coupled dielectric, piezoelectric, and pyroelectric properties, ferroelectric materials have been integrated into the state-of-the-art devices such as memories, logics, sensors/actuators, etc. Due to the inherent bi-stability of polarizations, the deterministic production of multiple states with distinct polarization values, however, remains a hallmark challenge. In this talk, I will discuss how to engineer and control the polarization switching in a deterministic manner. Leveraging the advanced thin film epitaxy and multi-scale characterizations, I will demonstrate the capability to control both the nanoscale switching events and mesoscale switching pathways in ferroelectric thin films. In particular, I will show the potential for tunable, multi-state polarization via control of switching kinetics in ferroelectrics. Here we observe a type of multi-state switching behavior in ferroelectrics wherein the intermediate polarization state can be deterministically written into a number of states in any order by varying the driving voltage. These states are found to be non-volatile, stable, and deterministically accessible, providing the functionality needed for the realization of solid-state adjustable synaptic weights for adaptive neuromorphic electronics.

 
Bio: Ruijuan Xu is a Ph.D. student in the Department of Materials Science and Engineering at the University of California, Berkeley. She earned a B.E. in Materials Science and Engineering from Zhejiang University in China in 2011 and a M.S. in Materials Science and Engineering from University of Illinois at Urbana-Champaign in 2014. Her research interests are using advanced thin film epitaxy and nanofabrication to design and synthesize novel complex oxide materials and artificial architectures, and using multi-scale characterizations to probe and control material properties at the nanoscale.