报告摘要：
Heat transfer in solids provides a window for scientific study of solid state physics, and also plays a pivotal role for a wide range of industry applications. Although it is a traditional research focus in mechanical engineering, study of heat transfer from materials physicists’ perspective would result in new discovery, new insight and new potential applications.
In this talk, I will show our recent work on understanding novel charge dynamics of vanadium dioxide by investigating its electronic thermal conductivity across its metal-insulator phase transition. An unusually low electronic thermal conductivity is found, and different from previously established conduction mechanisms, it is a signature of the absence of quasiparticles in a strongly correlated electron fluid where heat and charge diffuse independently.
I will also share another story of ion-written micro-thermotic platform. We demonstrate a monolithic material structure on which nearly arbitrary microscale thermal metamaterial patterns can be written and programmed. It is based on a single, suspended membrane whose thermal conductivity is locally, continuously and reversibly engineered over a wide range and with fine spatial resolution by focused ion irradiation. Our thermal cloak and thermal rectifier demonstrations show how the platform can be used to create thermal metamaterials that control heat flow at the microscale.

报告人简介：
Professor Junqiao Wu received a B.S. from Fudan University and a M.S. from Peking University, China. He obtained a Ph.D. degree from the University of California, Berkeley for work on nitride semiconductors and highly mismatched semiconductor alloys. He did postdoctoral research in the Department of Chemistry and Chemical Biology at Harvard University on phase transitions in transition metal oxide nanomaterials. He began his faculty appointment in the Department of Materials Science and Engineering at UC Berkeley in 2006. His honors include the Berkeley Fellowship, the 29th Ross N. Tucker Memorial Award, the U.C. Regents' Junior Faculty Fellowship, the Berkeley Presidential Chair Fellowship, the US-NSF Career Award, the US-DOE Early Career Award, the Presidential Early Career Award for Scientists and Engineers (PECASE) from the White House, the Outstanding Alumni Award from Peking University China, and the Bakar Faculty Fellows Award. He is currently the Chair of the Applied Science and Technology Graduate Group at UC Berkeley, and holds joint appointment at the Lawrence Berkeley National Laboratory, and adjunct professorship at Peking University and the Tsinghua-Berkeley Shenzhen Institute.
The Wu group explores novel properties and applications of strongly correlated electron materials, phase transitions at the nanoscale, and optoelectronic, thermal and thermoelectric properties of semiconductor alloys and interfaces. Prof. Wu has published over 200 widely cited papers in these fields.