2022 Fiscal Year Final Research Report
Photoinduced crystal-crystal phase transition dynamics of resonantly bonded crystals for the next-generation information recording technology
| Project/Area Number |
21K14400
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 26020:Inorganic materials and properties-related
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
2021-04-01 – 2023-03-31
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| Keywords | 光物性 / 時間分解分光法 / 超高速現象 / 相変化材料 |
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| Outline of Final Research Achievements |
Phase-change materials, which are used in DVDs and other media, have the unique bonding called resonance bonding in the crystalline phase. This bonding causes a difference in reflectance between the crystalline and amorphous phases of the phase-change material. Currently, in DVDs, the digital information is recorded by controlling the two phases by laser irradiation. In this study, we studied the optical change and the phase transition dynamics during the crystal structure phase transition of resonantly bonded crystals. The dynamics of the phase transition and optical changes were investigated by time-resolved optical spectroscopy using a femtosecond laser. In the orthorhombic-cubic PbGeTe system, coherent optical phonons disappear under strong excitation conditions, indicating a phase transition behavior, and changes in optical properties are observed.
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| Free Research Field |
光物性
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| Academic Significance and Societal Importance of the Research Achievements |
現状の光相変化材料は結晶相-アモルファス相間の相転移を利用している．アモルファス化には高い強度の光照射を行う必要があり，かつ原子の拡散を要する機構であるため，省エネルギー化・高速化を目的として，物性の変化を伴う結晶-結晶相転移を利用する結晶性の相変化材料の開発が試みられている．本研究は，過去に明らかになった，共鳴結合を有する光相変化材料が，原子の熱振動のような格子系の変化で光学特性が大きく変化することに着目し，結晶構造相変化を示す共鳴結合結晶に期待される相転移の前後の光学特性変化を調査するものである．本研究の遂行は，従来材料よりも高速な結晶性の相変化材料の開発指針となる．
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