Multiferroics in Dirac electron materials

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H02108
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: The University of Tokyo
• Principal Investigator: Ogata Masao 東京大学, 大学院理学系研究科(理学部), 教授 (60185501)
• Co-Investigator(Kenkyū-buntansha): 福山 秀敏 東京理科大学, 理学部第一部応用物理学科, 教授 (10004441) ; 鈴村 順三 名古屋大学, 理学研究科, 名誉教授 (90108449) ; 小林 晃人 名古屋大学, 理学研究科, 准教授 (80335009) ; 伏屋 雄紀 電気通信大学, 大学院情報理工学研究科, 准教授 (00377954) ; 白石 誠司 京都大学, 工学研究科, 教授 (30397682) ; 田嶋 尚也 東邦大学, 理学部, 教授 (40316930)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: ディラック電子 / マルチフェロイクス

Outline of Final Research Achievements

We clarified the following points about the multiferroics realized in the Dirac electron materials. 1) Due to the relativistic symmetry of the Dirac electron system, there is a remarkable relationship between the dielectric constant, responses to the magnetic and electric fields, and diamagnetic orbital susceptibility. An exact formalism of the magnetic susceptibility has been obtained. 2) About the intrinsic spin Hall effect in bismuth, a basic theory about the magnetic moment is established. Experimentally, the behavior of the spin current is clarified by using the thin film of bismuth. 3) In the Dirac electron systems in organic conductors, the results of NMR are interpreted by the electron correlation. The existence of the loop of Dirac points is shown. Experimentally, the valley degrees of freedom are found in the analysis of the magneto-resistivity.

Free Research Field

固体物理学