Origin and real-space observation of phasons in rare-earth iron oxides with modulated structures

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03431
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Asaka Toru 名古屋工業大学, 工学(系)研究科(研究院), 准教授 (80525973)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: フェイゾン / 変調構造 / 電荷秩序 / 希土類鉄酸化物 / 透過型電子顕微鏡

Outline of Final Research Achievements

This study aimed to understand the electron-beam-induced phasons in a charge-ordered rare-earth iron oxide (Yb2Fe3O7) through real-space observations mainly using scanning transmission electron microscopy (STEM) and to clarify their origin and excitation mechanism. Furthermore, in-situ observations were performed using an electron microscope to explore the possibility of controlling physical properties via phasons.
The observed phasons were suggested to be correlated with changes in charge order due to electron beam irradiation, and electron-beam-induced phasons were also observed in other rare-earth iron oxides (RFe2O4, R is a rare-earth element) with similar charge order. In addition, in-situ high-resolution TEM observations were performed on the present compound under applied electric fields, and IV measurements were also successfully performed simultaneously.

Free Research Field

無機構造物性

Academic Significance and Societal Importance of the Research Achievements

物質の結晶構造は通常、特定の対称性と周期で無限に連続するものであるが、中には基本周期とは異なる長周期の規則性が付け加わった構造がある。そのような構造を変調構造という。変調構造をもつ結晶では通常の結晶では現れることのないフェイゾンという素励起が生じることが期待される。本研究では希土類と鉄の複合酸化物に対して電子線で誘起したフェイゾンを観測し、その起因を主に電子顕微鏡を用いて調べた。その結果、電子線誘起フェイゾンは価数の異なる鉄の規則的配列の変化によるものと考えられた。