As a textbook example of strongly correlated electron material, vanadium dioxide (VO2) features a metal-insulator transition (MIT) when temperature drops below 67oC. The physics of the MIT has challenged physicists for decades, while the potential of the MIT has inspired researchers for a wide range of applications. In this lecture, I will talk about two of our recent works. On the fundamental side, we have revealed novel charge dynamics of VO2 by investigating its electronic thermal conductivity across the MIT [Science, 355, 371(2017)]. An unusually low electronic thermal conductivity was found, and different from previously established conduction mechanisms, it is a signature of absence of quasiparticles in a strongly correlated electron fluid where heat and charge diffuse independently. On the applied side, we have developed new applications of VO2 for smart regulation of thermal infrared radiation, including a platform where thermal emissivity can be engineered for infrared camouflaging [Advanced Materials, 32, 1907071 (2020)], a thermal imaging sensitizer that achieves milli-Kelvin resolution of thermography at room temperature [Science Advances, 6, eabd8688 (2020)], and a temperature adaptive radiative coating for all-season household thermal regulation [Science, 374, 1504 (2021)].
Professor Junqiao Wu received a B.S. from Fudan University and a M.S. from Peking University, China, both in physics. He obtained a Ph.D. degree in applied physics from the University of California, Berkeley, and did postdoctoral research in chemistry at Harvard University. He began his faculty appointment in the Department of Materials Science and Engineering at UC Berkeley in 2006. His honors include the 29th Ross N. Tucker Memorial Award, 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, elected Fellow of the American Physical Society (APS), and the title of Clarivate Highly Cited Researcher. He is currently the Chair of the Applied Science and Technology Graduate Group at UC Berkeley (the largest interdisciplinary PhD-level research program on campus), and also holds a joint appointment at the Lawrence Berkeley National Laboratory. The Wu group explores physics and applications of electronic materials. Prof. Wu has published over 200 widely cited papers in these fields.