Development of multifunctional materials by structure control of nanogranular films

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06849
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural/Functional materials
• Research Institution: Research Institute for Electromagnetic Materials
• Principal Investigator: Ikeda Kenji 公益財団法人電磁材料研究所, その他部局, 研究員(移行) (40769569)
• Co-Investigator(Kenkyū-buntansha): 薮上 信 東北大学, 医工学研究科, 教授 (00302232) ; 小林 伸聖 公益財団法人電磁材料研究所, その他部局等, 研究員(移行) (70205475)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: ナノグラニュラー薄膜 / 磁気誘電効果 / 誘電率

Outline of Final Research Achievements

To develop new functional materials such as magnetic field control of dielectric property, we have studied the high frequency electric and magnetic properties in multi-layered nanogranular FeCo-MgF films, consisting of layer stacking of nanometer-sized magnetic granules dispersed in an MgF insulator matrix. The frequency dependence of relative permittivity is described by the Debye-Frohlich model, taking relaxation time dispersion into account, which reflects the microstructure, such as granule size, the inter-spacing between the granules, and multi-layer structure. Relative permittivity of multi-layered nanogranular films increased with the number of laminations, which is attributed to the increase in relative permittivity not to depend on the frequency. The increase of relative permittivity caused by the formation of layered structure was kept to THz frequency band, which is probably caused by the electric polarization at the interface between the layers.

Free Research Field

磁性薄膜

Academic Significance and Societal Importance of the Research Achievements

従来のナノグラニュラー薄膜は、磁性金属と絶縁体マトリックスの比率によってその特性の大半が決定され、支配的な制御要因となっていた。今回の検討では、積層構造の形成により誘電率の増加が確認された。この結果は、積層構造の形成に伴う内部構造の変化によって特性制御が可能であることを示すものであり、ナノグラニュラー構造の新たな制御要因を見出した点でその学術的意義は大きい。積層構造による誘電率の制御は、今後の光学応用にとっても有用な結果である。