（2001）重い電子の秩序化要点

研究領域名

　重い電子系の形成と秩序化

領域代表者

　上田　和夫（東京大学･物性研究所･教授）

研究期間

　平成20年度～24年度

研究の概要

　重い電子系と呼ばれる希土類およびアクチノイド化合物では、電子の見かけ上の質量が数百倍から千倍に増大する。これまでその理解は、電子の遍歴性と局在性の競合に基づいていた。近年、重い電子系を舞台に次々と発見される新しい超伝導や磁性現象を理解するには、電荷とスピンに加えて、軌道や格子の自由度も絡んだ電子の多自由度性を考慮することが必要となっている。本領域では、遍歴・局在という伝統的な横糸と多自由度性という新たな縦糸が織りなす系を舞台に、重い電子形成の直接観測、非調和格子振動による新奇物性の発現と理解、新超伝導相や新多極子相の探索と理解、磁性と超伝導の新概念創出を目指し、重い電子系研究の展開を図る。

Title of project

Emergence of Heavy Electrons and Their Ordering

Head Investigator Name

Kazuo Ueda

Term of Project

2008-2012

Abstract of Research Project

“Heavy electron states” emerge in rare-earth and actinide compounds, when f electron exhibits huge effective mass which is a few hundred or thousand times as large as the bare electron mass. Thus far, the heavy electron state has been comprehensively understood by the competition between itinerant and localized nature of f electron. However, in order to understand new superconductivity and magnetism which have been recently discovered in heavy electron systems, it is essentially important to consider multi degrees of freedom such as f-electron orbital and anharmonic phonon (rattling) in addition to spin and charge. In this innovative research area, we will develop heavy-electron research on the system characterized by new elements of multi degrees of freedom in combination with traditional concept of the competition between the itinerant and localized nature of f electron. The target of this project is to establish new concepts of superconductivity and magnetism through the direct observation of heavy electron state, understanding of electron-rattling state, and exploring exotic superconductivity and novel multipole ordering.