A research team from the Graduate School of Engineering at the University of Tokyo, in collaboration with the National Institute of Advanced Industrial Science and Technology, Hiroshima University, and the Japan Agency for Marine-Earth Science and Technology, has developed an innovative magnetic memory device. This device has a unique functionality that not only possesses the ability to store the history of applied voltages, a characteristic typical of memristors, but it also can store the history of applied magnetic fields under a constant applied voltage. The device is composed of a germanium (Ge) semiconductor channel and ferromagnetic/insulator/semiconductor multilayer electrodes. Remarkably, the researchers achieved an extremely large magnetoresistance ratio of up to 32,900% — a performance that is 30 to 100 times greater than the magnetoresistance ratios of magnetic tunnel junctions used in current commercial magnetic random-access memory (MRAM). This breakthrough is a result of uniting two previously distinct fields: spintronics and memristor research. The achievement paves the way for next-generation technologies, including advanced magnetic memory, highly sensitive magnetic sensors, and cutting-edge neuromorphic computing systems.
Device operating principle based on experimental results: A two-terminal device with an n-type Ge (n–-Ge) channel and Co/Fe/MgO/Ge(Ge:B)/Ge electrodes. The memory function can be attributed to the ferromagnetic filaments formed by Mg vacancies in MgO and impact ionization in the n–-Ge channel.
Papers
Journal: Advanced Functional Materials
Title: Giant memory function based on the magnetic field history of resistive switching under a constant bias voltage
Authors: Masaya Kaneda*, Shun Tsuruoka, Hikari Shinya, Tetsuya Fukushima, Tatsuro Endo, Yuriko Tadano, Takahito Takeda, Akira Masago, Masaaki Tanaka, Hiroshi Katayama-Yoshida, and Shinobu Ohya*