2013年11月12日（周二）上午10点，物理系seminar：

报告题目： Physics and Chemistry of Complex Oxide Heterostructures 报告人： Ying-Hao Chu Department of Materials Science & Engineering, National Chiao Tung University, Taiwan 报告时间： 2013-11-12 10:00 报告地点：理科楼三楼报告厅摘要： Condensed matter physics and solid state chemistry is the cornerstone for building up next-generation functional devices. Recently, complex oxide heterostructures provide a powerful route to manipulate the charge, spin, orbital, and lattice degrees of freedom, resulting in a number of exciting discoveries on intriguing phenomena. The atomic foundry of complex oxide in National Chiao Tung University serves as a platform to provide deep understanding of complex oxide heterostructures and to create a huge playground for condensed matter research. In this presentation, several model systems will be demonstrated to illustrate the key advantages of this foundry. In the first example, the ferromagnetic La0.7Ca0.3MnO3/superconducting YBa2Cu3O7-x heterostructures of two distinct interfaces with atomically precise interface control have been fabricated to explore the coupling between these two functional layers. Samples with different termination type show distinct superconductivity and magnetism properties together with different valence states of Mn. A new mechanism of charge transfer in these heterostructures was revealed. This mechanism is critical to the superconductivity and magnetism in these heterostructures. In the second example, we broaden an insight to show the heteroconjugation of complex oxide nanocrystals, which can provide a powerful route to manipulate their tunable properties by means of strain engineering. In order to demonstrate this structure, we chose BiFeO3 as a model system. A rather unique feature of this material found in the thin film system is that its phase stability is tunable if an appropriate external constraint is imposed on it; precisely, rhombohedral phase can be transformed into a tetragonal-like phase. According to our demonstration, this phase transition is valid not only for thin film, but also for nanocrystal. This work suggests a new pathway to explore the possibility of strain engineering on nanocrystals and broaden their practical applications in order to meet the demands of multi-functionalities. In the third example, complex oxide–noble metal hybrids were successfully fabricated and characterized. The properties of the composed phases strongly depend on the interplay between the complex oxide and noble metal nanocrystals. These results suggest that the wide range of functionalities in complex oxides can serve to enlarge the playgroup of nanocrystal conjugation and create a new pathway to use complex oxide conjugated nanocrystals for practical applications.