Verification of gradon as a localized atomic vibrations in inhomogeneous matereials with mass gradient

2014 Fiscal Year Final Research Report

• Project/Area Number: 24654080
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics I
• Research Institution: Tohoku University
• Principal Investigator: IWASA Kazuaki 東北大学, 理学(系)研究科(研究院), 准教授 (00275009)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: フォノン / 質量勾配物質 / 中性子散乱 / X線回折

Outline of Final Research Achievements

Materials are characterized by crystal structures represented in terms of atomic spatial arrangement and vibrations. Cooperative vibration of atomic groups is called phonon (lattice vibration), and it has been investigated for homogeneous systems in detail. In the present research, phonon modes in materials with mass gradient and in materials exhibiting structural transformations are investigated. As one topic of the latter issue, anomalously low-frequency phonon modes are discovered in the rare-earth hexaboride GdB6, TbB6, and DyB6. In particular, these exhibit inhomogeneous state in which micro domains of the low-temperature structure survive at much higher temperature than reported previously. This inhomogeneous structural fluctuation is expected to influence on electrical and thermal conductivity.

Free Research Field

固体物理学