摘要

Interfaces have emerged as key focal points of current condensed matter science.  In complex, correlated oxides, heterointerfaces provide a powerful route to create and manipulate the charge, spin, orbital, and lattice degrees of freedom. The most common interfaces that have been explored are artificially constructed heterointerfaces and naturally formed homointerfaces. The interaction of degrees of freedom at the heterointerface has resulted in a number of exciting discoveries including the observation of a 2-D electron gas-like behavior at LaAlO3-SrTiO3 interfaces; the emergence of the ferromagnetism in a superconducting material at a YBa2Cu3O7-x-La0.7Ca0.3MnO3 interface. Recently, several key studies pointed out interesting observations on homointerfaces, domain walls in multiferroics, including an observation of insulating interlocked ferroelectric and structural antiphase domain walls in YMnO3 system, the source of the exchange bias interaction between the ferromagnetic metal layer and multiferroic, and local conduction in BiFeO3. These complex oxide interfaces create a huge playground to discover new emergent phenomena. The key question I would like to address: how can we control the functionalities at complex oxide interfaces? In the beginning, I will take LaAlO3-SrTiO3 interface as a model system to illustrate the concept of ferroelectric control to induce metal-insulator transition. Then, I will take domain walls in BiFeO3 as a model system to demonstrate the ability to tune the homo-interface by strain engineering. In the end, I will introduce a new type of oxide interfaces. We found that there is one more category, which has been widely demonstrated: epitaxial self-assembling nano-composites. Such a heterostructure has been shown to enhance or create properties by interface-mediated coupling or local confinement. However, there is no systematical study on the interfacial properties in these nano-composites. The key concept is to treat these interfaces as tubular oxide interfaces. I will show the conduction located at the interfaces of vertical heterostructures in BiFeO3-CoFe2O4. Such results open new pathways to create the interfacial properties of complex oxide interfaces.

报告人简介

Professor Ying-Hao Chu received his PhD in the Department of Materials Science & Engineering from National Tsing-Hua University in 2004. He joined University of California, Berkeley in 2004 as a postdoc. In 2008 he joined National Chiao Tung University in the Department of Materials Science & Engineering as an assistant professor. His research is highly focused on complex functional oxides and nanostructures. He has extensive experience in the use of advanced characterization techniques to understand and manipulate complex functional oxides and nanostructures. His papers have been published in Science (1), PNAS (2), Nature X (>10), Physical Review L&B (>25), Nano Letters & ACS Nano (>15), Advanced (Functional) Materials (>10), APL/JAP (>40), >10 invited review papers and etc. His current goal is try to create a pathway to use topological defects for next generation electronics. Now, he is top 3 of most publication in BiFeO3 and top 10 of most publication in multiferroic materials.