Creation and Mechanical Design of Atomic-scale Multiferroics by Functionalized Defect Engineering

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02027
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Kyoto University
• Principal Investigator: Shimada Takahiro 京都大学, 工学研究科, 教授 (20534259)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 格子欠陥 / 強誘電体 / 磁性 / マルチフィジックス特性 / 第一原理解析

Outline of Final Research Achievements

In this study, we focused on lattice defects such as atomic vacancies and dislocations and performed first-principles calculations based on quantum mechanics, and revealed that atomic-scale microscopic magnetism and ferroelectricity, which do not exist in the host material, can be created in the lattice defects. In other words, we have shown that atomic-scale multiferroics can be created by engineering lattice defects, and overcome the conventional notion that ferroelectricity cannot exist below the critical nanoscale size. The structure-property relationship and the possibility of structural design were also demonstrated here. Furthermore, we have investigated the coupling of novel properties with applied strain (multiphysics), and have provided a guideline for controlling the lattice defect function in terms of mechanics.

Free Research Field

計算材料力学

Academic Significance and Societal Importance of the Research Achievements

本研究は、力学的な負荷ひずみと、従来は材料機能を劣化させる因子として忌避されてきた欠陥によって新奇な磁性強誘電体を創り出すことで、材料力学的観点に基づく全く新しい機能創成の可能性を開拓した点にその学術的意義がある。特に、臨界寸法以下の強誘電性は存在し得ないという従来概念を覆し、格子欠陥によって究極的に小さな原子寸法の磁性強誘電体の可能性を示した点にその特徴がある。また、負荷・電場・磁場の複合力場による複数の極性(磁気モーメント・分極)を利用した新規情報記録デバイスの超大容量化などの新しい技術を開拓するためのナノ機能要素を示した点に産業応用としての社会的意義がある。