Revalidation of Raman scattering spectroscopy using circularly polarized light

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K21854
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 13:Condensed matter physics and related fields
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Satoh Takuya 東京工業大学, 理学院, 教授 (40451885)
• Project Period (FY): 2019-06-28 – 2021-03-31
• Keywords: ラマン散乱 / 円偏光 / フォノン / マグノン

Outline of Final Research Achievements

The optical magnon (Kaplan-Kittel exchange resonance mode) in the ferrimagnetic material YIG was observed using circularly polarized Raman scattering, and the temperature dependence of the frequency was precisely measured. From the results, the exchange interaction constant was accurately determined.
Furthermore, circularly polarized Raman scattering measurements were performed on the multiferroic material BiFeO3 to identify the mode of phonons, which had not been precisely determined. We also measured the temperature dependence of each phonon frequency and considered the possibility of spin-phonon coupling.
From the above results, one can conclude that circularly polarized Raman scattering has achieved mode detection and mode identification that could not be obtained by linearly polarized Raman scattering alone.

Free Research Field

磁気光学

Academic Significance and Societal Importance of the Research Achievements

円偏光を用いたラマン光学活性(ROA)は以前から知られていたが、その効果は小さく、また適用できる対象物質はキラル物質等に限られていた。円偏光ラマン散乱をモードの同定として用いるという本研究手法は原理が単純明快であり、幅広く様々な結晶に対して適用可能であるため、フォノンやマグノン振動モードの解析、マグノン探索において極めて強力な手法となるであろう。