Research on novel quantum phenomena of correlated topological semimetal

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H01171
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: University of Tsukuba
• Principal Investigator: Fujioka Jun 筑波大学, 数理物質系, 准教授 (80609488)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 強相関電子系 / トポロジカル半金属 / 遷移金属酸化物 / モット転移

Outline of Final Research Achievements

We have clarified that the perovskite-type CaIrO3 exhibits the high mobility Dirac electron, regardless of the strong electron correlation regime nearby the Mott transition by means of quantum transport measurements. The results of quantum oscillation and theoretical calculation demonstrate the emergence of Dirac electron system with dilute carrier density and high mobility exceeding 60,000 cm2/Vs. We also found that the quantum limit is reached above around 10 T, in which the large positive magnetoresistivity with magnetoresistivity ration more than 5,500% emerges. The numerical calculation suggests that the electronic ordering due to the magnetically induced quasi-one dimensional confinement causes the electronic ordering such as the charge density wave in the quantum limit.

Free Research Field

強相関電子系

Academic Significance and Societal Importance of the Research Achievements

ディラック半金属は電子系のトポロジーを研究する典型的な物質の一つで、高い移動度を持つ相対論的固体電子(ディラック電子)による量子現象が見られる特徴がある。従来の多くの研究は一電子近似が成り立つ系を対象にしてきたのに対し、本課題では電子間の相互作用が強い系を対象にし、高移動度ディラック電子の量子輸送特性や相互作用に由来する現象を実験的に観測する事に成功した。従来の電子間相互作用が弱いディラック半金属とは質的に異なる現象も見られており、今後さらに研究を進める事で強く相互作用し合うディラック電子に特有の物理学の発展や電子機能性の開拓が期待できる。