Place : IRIG/SPINTEC, auditorium 445 CEA Building 10.05 (presential access to the conference room at CEA in Grenoble requires an entry authorization. Request it before April 15th at admin.spintec@cea.fr)
video conference : https://univ-grenoble-alpes-fr.zoom.us/j/98769867024?pwd=dXNnT3RMeThjYStybGVQSUN0TVdJdz09
Meeting ID: 987 6986 7024
Passcode: 025918
Abstract : Spin-orbit torque (SOT) induced magnetization switching is a complex technology currently of great interest for various spintronic applications. It can potentially revolutionize nonvolatile embedded memory, such as magnetic random access memory (MRAM), logic devices, and true random number generators. These devices require a few nanometer-thick materials with perpendicular magnetic anisotropy (PMA) for high bit density, significant SOT efficiency to reduce writing current and energy consumption, and external field-free switching. Above all, the SOT materials must be semiconductor fabrication-friendly. However, only a few material sets and their heterostructures fulfill the requirements. In our recent research, we have faced the challenge of exploring various alloying elements, including Ta, N, V, Si, and Ti, in the β-phase W matrix as a spin-current-generating layer with enhanced SOT efficiencies. We employ first-principles energy-band calculations to narrow down the compositional ranges where we can obtain high-spin Hall conductivity values. Then, we deposit nonmagnetic/ferromagnetic heterostructures and pattern them into devices. For example, we confirm that the heterostructure consisting of β-W-Si (4 at%)/CoFeB exhibits PMA, a high damping-like SOT efficiency (~0.58), and low longitudinal resistivity (~135 μΩ cm). The heterostructures withstand 500ºC post-deposition heat treatment. Furthermore, we estimate write power consumption 10 times lower than that of the heterostructure based on pristine β-W and other materials. These findings highlight the complexity of the task and the potential for significant advances in next-generation MRAM applications.
Biography : Professor Kim has worked in the Department of Materials Science and Engineering at Korea University, Seoul, Korea, since 2000. Before joining Korea University, he worked for Samsung Electro-Mechanics in Korea and Quantum Corporation in the USA. Prof. Kim received the Korean Government’s National Order of Service Merit-Green Stripes in June 2017. He is the recipient of all three major awards at Korea University: The Research Awards in 2022 and 2021, the Technology Award in 2016, and the Teaching Award in 2005. Prof. Kim received the Kang II-Koo∙Hyundai BNG Steel Award in 2025 and the Amo Award in 2019 from the Korean Magnetics Society (KMS). He received the Iljin Academic Achievement Award from the Korean Institute of Metals and Materials (KIM) in 2015. He has published over 330 peer-reviewed journal papers, holds over 150 registered patents, and has delivered over 150 invited talks. Prof. Kim’s research interests include the development of novel magnetic thin films and nanostructured materials for spintronic memory devices, semiconductor metallization, and sustainability and biomedical applications.