DATE2024.04.26 #Press Releases
Success in Controlling Magnetic States of Antiferromagnets Using Exchange Bias
--A major step toward ultra-fast and ultra-low-power memory--
Summary of Presentations
A research group led by Graduate Student Mihiro Asakura, Project Associate Professor Tomoya Higo, and Professor Satoru Nakatsuji at the Graduate School of Science, The University of Tokyo, has discovered that the magnetic order in Weyl antiferromagnet Mn3Sn, which has attracted attention as a next-generation nonvolatile memory material, can be controlled by exchange bias.
Amidst increasing data demands due to advances in information, communication, AI, and IoT technologies, there is a pressing need for faster, more power-efficient information processing technologies beyond traditional silicon-based semiconductors. Magnetoresistive Random Access Memory (MRAM), a nonvolatile memory that retains data without power consumption, addresses this need. By substituting ferromagnetic materials in MTJ devices by antiferromagnetic materials, it is possible to dramatically increase the operating frequency from the GHz band to the THz band. Therefore, development of antiferromagnetic materials for MRAM is currently underway to realize memory that is both nonvolatile (power-saving) and ultra-fast.
The research group has developed the Weyl antiferromagnet Mn3Sn, in which the topological electronic state plays an important role, and has demonstrated that Mn3Sn is a suitable antiferromagnetic material for memory application as an alternative to ferromagnetic materials through the realization of the electrical writing (published in Nature in 2020 and 2022, press release (1), (2)) and reading (published in Nature in 2023, press release (3)) of nonvolatile data (magnetic state), an essential function for MRAM applications (Figure).
Figure: MTJ device configuration
(a) Configuration of MTJ device using ferromagnetic materials. From the bottom, there are a recording layer to store information as a magnetic state, a reference layer for comparing the magnetic state with the recording layer when reading out, and a pinning layer for fixing the magnetic state of the reference layer by exchange bias. (b) All-antiferromagnetic device, in which the ferromagnetic layers are replaced by the Weyl antiferromagnet. The writing and reading phenomena have already been demonstrated, and in this study, the effect of fixing by exchange bias is demonstrated.
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Journal name Advanced Materials Title of paper