报告题目： Nanoscale Magnetization Reversal by Electric Field-Induced Ion Migration
Prof. Dr. Run-Wei Li is the director of Key Laboratory of Magnetic Materials and Devices, Chinese Academy of Sciences (CAS). He obtained his Ph.D. degree from Institute of Physics (IOP), CAS in 2002, then worked in Osaka University, Japan as a JSPS (Japan Society for the Promotion of Science) research fellow, and in Kaiserslautern University, Germany as an AvH (Alexander von Humboldt) research fellow. In 2005, he joined in the International Center for Young Scientists, National Institute for Materials Sciences, Japan as a senior research fellow. He joined in NIMTE as a full professor in 2008. Now his research interests focus on flexible functional materials and devices for storage and sensors. He has filed more than 100 patents and published more than 200 papers in peer-reviewed journals. He serves as a referee for over 50 international journals such as: Nat. Nanotech., Nat. Commun., Adv. Mater. and etc.
Reversibly controlling the nanoscale magnetization at room temperature by electric field means would enable the development of various spintronic devices, in particular, novel magnetic information storage devices. Although several approaches have been developed so far to achieve electrical modulation of magnetization reversal, most of these methods suffer from practical issues that hinder them from direct applications. In this talk, we will present our recent progresses on nanoscale magnetization reversal caused by electric field-induced ion migration in oxide thin films. We observed that in ferrite films the nanoscale magnetization can be reversibly and nonvolatilely reversed at room temperature via an electrical ion-manipulation approach, wherein the application of electric fields with appropriate polarity and amplitude can modulate the size of magnetic domains with different magnetizations up to 70 % [1, 2]. We also utilized the high-throughput synthesis approach, namely, combinatorial substrate epitaxy, to understand the degree of ionic migration in different orientations . It was determined from the analysis that the  crystal direction exhibits the maximum nanoscale magnetization reversal ratio. This is mainly attributed to the ease Co2+ migration in the  direction under the electric field assisted by a Fe3+ and oxygen vacancies.