纳米加工技术在基础科学研究中的应用||本周物理学术讲座

报告人：陈宜方，复旦大学

时间： 8月31日（周四）10:00

单位： 中科院物理研究所

地点：M楼236报告厅

纳米加工技术的兴起与发展极大的推动了各个科学领域的基础研究。复旦大学针对国家在自上而下的纳米光刻与制造技术上的落后现状，响应当前纳米科学技术的发展需求，瞄准国际先进水平和未来发展趋势，充分利用“复旦大学微纳科技平台”拥有的国际先进的、完整的现代化加工设备和条件，建立起了具有国际水平的纳米加工工艺基础。目前正在将这个工艺技术应用到纳米电子、纳米光子学（包括可见光波段的超材料、超表面材料、超分辨聚焦、光场调控、纳米仿生学）和X射线光学部件的研制等领域，取得了一定的成果。这个报告将首先向大家汇报复旦大学在自上而下的纳米加工技术研发上的进展，然后将通过几个典型的应用案例来阐述纳米加工技术在基础研究中的应用和重要性。其中，在纳米电子学领域，将简要介绍在太赫兹波InP基高电子迁移率晶体管（InP-HEMTs）、硅纳米线光电器件和红外偏振探测器的纳米加工与表征；在超表面材料方面，将介绍采用纳米结构进行高效率光场调控、局域表面等离子体结构色及其在高分辨率彩色印刷中的应用；在超分辨聚焦方面，将介绍基于光子纳米喷射效应（Nanojet effect）的超分辨透镜研制、在纳米仿生学方面，将介绍蝴蝶翅膀多层结构（Lamellae layer）的研制及其光学结构色表征和研究、在X射线光学部件的研制方面，将介绍我们在衍射光学部件（菲涅尔波带片、均匀辐照的汇聚透镜、分辨率测试卡）关键技术的研发。希望通过这个交流，能够进一步增进双方的交流、建立起更广泛的交流与合作，进一步扩展纳米加工技术在各个学科领域的应用。

报告人：Hiroaki Misawa，Hokkaido University and National Chiao Tung University

时间：8月29日（周二）10:00

单位：北京大学现代光学研究所

地点：物理楼中215

We have also constructed an artificial-photosynthesis system that produces NH3 by a photofixation of a N2 molecule based on visible light irradiation. Ruthenium was used as a co-catalyst for the NH3 synthesis. The action spectrum of apparent quantum efficiency of NH3 evolution showed good agreement with the LSPR band. In addition, we revealed that NH3 could be obtained with ~100% selectivity by using zirconium/zirconium oxide co-catalyst. These findings blaze new methods for energy-efficient photocatalytic production of NH3 using solar light, water, and N2 gas.

报告人：Hendrik Ohldag，SLAC National Accelerator Laboratory

时间：8月29日（周二）14:00

单位：中科院物理研究所

地点：D楼212报告厅

Today’s magnetic device technology is based on complex magnetic alloys or multilayers that are patterned at the nanoscale and operate at gigahertz frequencies.To better understand the behavior of such devices one needs an experimental approach that is capable of detecting magnetization with nanometer and picosecond sensitivity. In addition, since devices contain different magnetic elements, a technique is needed that provides element-specific information about not only ferromagnetic but antiferromagnetic materials as well. Synchrotron based X-ray microscopy provides exactly these capabilities because a synchrotron produces tunable and fully polarized X-rays with energies between several tens of electron volts up to tens of kiloelectron volts. The interaction of tunable X-rays with matter is element-specific, allowing us to separately address different elements in a device. The polarization dependence or dichroism of the X-ray interaction provides a path to measure a ferromagnetic moment and its orientation or determine the orientation of the spin axis in an antiferromagnet. The wavelength of X-rays is on the order of nanometers, which enables microscopy with nanometer spatial resolution. And finally, a synchrotron is a pulsed X-ray source, with a pulse length of tens of picoseconds, which enables us to study magnetization dynamics with a time resolution given by the X-ray pulse length in a pump-probe fashion.

报告人：Miao Liu，Lawrence Berkeley National Laboratory

时间：8月30日（周三）15:00

单位：中科院物理研究所

地点：M楼253会议室

In this presentation, we will show our detailed work, based on the robust automated high-throughput density functional calculations and the high-quality theoretical data from Materials Project, to systematically evaluate the electrochemical performance as well as the intercalating mobility of multivalent cation over several hundreds of host compounds. We will also demonstrate three of in-house theoretical attempts that have been designed and practiced to quantitatively gauge the multivalent cation mobility. Our study suggests that the matching between the intercalant site preference to the diffusion path topology of the host structure plays a decisive role to control mobility more than any other factor. Our “in silico” design and evaluation have found several promising Mg-ion cathode materials that possess improved Mg mobility (migration activation energy lower than 600meV), and some of them have been confirmed by experimental research teams recently. The results demonstrate that the data-driven computational materials science is a realistic tool to enable the successful development and optimization of new materials for energy dense multivalent batteries.

报告人：钟志诚，中科院宁波材料所

时间：9月1日（周五）10:00

单位：北京师范大学物理系

地点：科技楼A区311

Complex transition metal oxides in bulk form exhibit a huge range of physical properties. Heterostructures of transition metal oxides offer the prospect of greatly enhancing these properties or of combining them to realize entirely new properties and functionalities. In recent years I focused on some unique and general properties of oxide heterostructures. Today I will talk about (i) polarity induced oxygen vacancies in LaAlO3/SrTiO3 interfaces, and a structural reconstruction in cuprate thin films; (ii) theory of spin-orbit coupling in LaAlO3/SrTiO3 interface and SrTiO3 surfaces, and a proposal of giant switchable Rashba effect; (iii) unusual electronic states perovskite oxide heterostructure along (110); (iv) DFT + dynamical mean field theory (DMFT) results of strongly correlated oxide heterostructures such as SrVO3 and SrRuO3 ultrathin films.

报告人：Celso Grebogi，University of Aberdeen

时间：9月1日（周五）15:00

单位：北京师范大学物理系

地点：物理楼106

Many simple nonlinear deterministic systems can behave in an apparently unpredictable and chaotic manner. This realisation has broad implications in many fields of science. Some basic concepts and properties in the field of chaotic dynamics of dissipative systems will be reviewed in this talk, including transient chaos, fractal basin boundaries, and the control of chaos. I will then go a step further by introducing complex systems, made up of many states that are interrelated in a complicated manner. I will argue that the ability of a complex system to access different states, combined with its sensitivity, offers great flexibility in controlling the system’s dynamics to select a desired behaviour. I will use some of the properties of chaotic and complex systems in application topics, including the difficulty in constructing models of such systems.