Online ISSN: 1884-4111 Print ISSN: 0033-8303
Radioisotopes 65(7): 319-324 (2016)

連載講座Serial Lecture

III-5 無秩序系の低エネルギーダイナミクスIII-5 Low-Energy Dynamics in Disordered Materials

1日本原子力研究開発機構J-PARCセンターJapan Atomic Energy Agency, J-PARC Center ◇ 319–1195 茨城県那珂郡郡東海村大字白方2–4 ◇ 2–4 Shirakata, Tokai, Ibaraki Pref. 319–1195, Japan

2European Research Infrastructure Consortium, European Spallation SourceEuropean Research Infrastructure Consortium, European Spallation Source ◇ P.O. Box 176, SE-221 00 Lund, Sweden ◇ P.O. Box 176, SE-221 00 Lund, Sweden

発行日:2016年7月15日Published: July 15, 2016

一般にガラスやアモルファスと呼ばれる構造的に無秩序な物質は,比熱や熱伝導率といった熱輸送現象において低温領域で結晶とは異なる性質を普遍的に持つことが知られている。これらの熱的物性は,中性子非弾性散乱実験やラマン散乱実験で観測されるBoson Peakと呼ばれる低エネルギー励起と直接関連付けられる。また,中性子非弾性散乱実験で得られる振動状態密度は,普遍的低温熱物性に対する2準位系理論モデルの正当性を支持する。

Heat transport phenomena as the thermal conductivity or heat capacity in structurally disordered materials are different from those in crystal materials in low temperature region. These universal thermophysical properties in an atomic scale are directly related to the low-energy excitations, called Boson Peak, observed by neutron inelastic scattering and Raman scattering measurements. In addition, some results of the vibrational density of states obtained by neutron inelastic scattering measurement suggest the validity of two-level-system model which is widely accepted theoretical model of these universal thermophysical properties.

Key words: Neutron inelastic scattering; Disordered system; Boson Peak

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