What is it about?
In this study, we investigated the origin of the enhanced magnetic properties of nonvolatile magnetic random-access memory (MRAM) using first-principles calculations. MRAM is regarded as a promising next-generation memory technology because it can retain information without a continuous power supply. Owing to the increasing demand for energy-efficient information technologies, considerable research and development efforts have been devoted to the practical realization of MRAM. The Fe/MgO interface is one of the most promising structures for achieving high-performance MRAM devices. Recent experiments have shown that inserting a LiF monolayer at the Fe/MgO interface approximately doubles the perpendicular magnetic anisotropy (PMA). Because PMA is a key property governing the thermal stability and information retention capability of MRAM, understanding the mechanism responsible for this enhancement is of considerable importance. However, its microscopic origin has remained unclear. Our first-principles calculations revealed that the enhanced PMA originates from differences in the electron-density distribution between LiF and MgO, thereby providing a microscopic explanation for the experimentally observed enhancement.
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Why is it important?
Previous experiments have reported that the Fe/LiF/MgO structure exhibits significantly enhanced magnetic properties; however, the microscopic origin of this enhancement has remained unclear. To clarify the underlying mechanism, we performed non-collinear density functional theory (DFT) calculations, which fully account for all spin components, and constructed realistic Fe/LiF/MgO superlattice models to closely reproduce the experimental structures. Large-scale first-principles calculations were then carried out for these models. Our calculations revealed that LiF insertion approximately doubles the magnetic moment of the interfacial Fe atoms. This enhancement originates from a redistribution of the electron density associated with the Fe orbitals near the interface, which shifts toward the minimum-electron-density region located at the diagonal interstitial site of the LiF lattice. These findings provide a microscopic explanation for the experimentally observed enhancement and offer new design guidelines for developing high-performance nonvolatile magnetic memory materials.
Perspectives
This study elucidates the microscopic mechanism responsible for the enhanced magnetic properties of the Fe/LiF/MgO interface, providing a fundamental design principle for engineering magnetic interfaces. Future work will extend this approach to other interface materials and multilayer structures in search of even stronger perpendicular magnetic anisotropy. Close collaboration between theoretical and experimental studies will accelerate the realization of practical nonvolatile spintronic devices. We expect that the design principles established in this work will contribute to the development of next-generation energy-efficient memory technologies for a data-driven society.
Takuya Sekikawa
Read the Original
This page is a summary of: Mechanism of magnetization enhancement at the Fe/LiF/MgO interface elucidated through the first-principles calculations of the interface structure, Journal of Applied Physics, May 2025, American Institute of Physics,
DOI: 10.1063/5.0260903.
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