湖南大学“岳麓材料青年学者论坛” 第250期
题 目：原位透射电镜调控VO2中的金属绝缘转变
报告人： 程少博 教授 （郑州大学物理学院）
地 点： 两山一湖中三栋205会议室
时 间：2023年11月24日（周五）下午14:30-15:30
主持人： 马超 教授
邀请人： 材料科学与工程学院
报告摘要：
As a classic Mott insulator, VO2 has attracted worldwide attention because of its near room temperature metal-insulator transition. Using in situ transmission electron microscopy (TEM), we have systematically studied the transition mechanism of VO2 under electric field. The in situ biasing TEM experiments have shown that the stochastic conductivity in VO2 is due to the inherent stochasticity of monoclinic domain switching, which is helpful for generating random number. [1] Beside the volatile switching, we found the nonvolatile switching could also exist in VO2. With the help of the electroforming process, the Magnéli V5O9 phase will form (confirmed by TEM) and act as the conductive filament. Further experimental and theoretical results have shown that, by changing the voltage, temperature, and thickness of the film, the VO2 film could feature either volatile or nonvolatile switching. [2] Recent result has shown that VO2 could have giant nonvolatile photoinduced resistivity change under beam shining, [3] due to the injected carriers from the nearby CdS layer. This phenomenon has been studied by TEM, and electron energy loss spectroscopy results have shown that the hole doping will largely change the electronic structures and thus change the transportation behaviors of VO2, leading to an isostructural metal-insulator transition. [4]
References
[1] Shaobo Cheng, Min-Han Lee, Richard Tran, et al. Shyue Ping Ong, Ivan K. Schuller, Yimei Zhu*, Inherent stochasticity during insulator-metal-transition in VO2, PNAS, 118, 18 (2021)
[2] Shaobo Cheng, Min-Han Lee, Xing Li, et al. Operando characterization of conductive filaments during resistive switching in Mott VO2, PNAS, 118 (2021)
[3] H. Navarro, J. d. Valle, Y. kalcheim, et al. A hybrid optoelectronic Mott insulator, Appl. Phys. Lett., 118, 141901 (2021)
[4] Shaobo Cheng, et al. PNAS, in revision (2023).
报告人简介：
Prof. Shaobo Cheng obtained his Ph.D. degree from Tsinghua University in 2017. Then he joined McMaster University in Canada and Brookhaven National Laboratory in the US as postdoc researcher. He worked in Zhengzhou University as a full-time professor since early 2022. His current research interests are in transmission electron microscopy, functional oxides, and energy related materials.
