Study of pressure-induced topological transition and superconductivity in Type-II Dirac semimetal PdTe2

2023 Fiscal Year Final Research Report

• Project/Area Number: 20H01851
• 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: Niigata University
• Principal Investigator: Ohmura Ayako 新潟大学, 自然科学系, 准教授 (60425569)
• Co-Investigator(Kenkyū-buntansha): 名嘉 節 国立研究開発法人物質・材料研究機構, 機能性材料研究拠点, 主席研究員 (30344089) ; 石川 文洋 新潟大学, 自然科学系, 准教授 (50377181)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 超伝導物性 / 高圧物性

Outline of Final Research Achievements

We investigated the effect of pressure on the superconductivity of the type-II Dirac semimetal PdTe2 from the viewpoints of both physical properties and crystal structure. The pressure dependence of the superconducting transition temperature (Tc) decreases monotonically from 1 GPa to 6 GPa and has no change related to the theoretically predicted topological phase transition around 5 GPa. We also clarified that the Tc maximum at 1 GPa is not attributed to the pressure variation of carrier density but depends on that of the Debye temperature (lattice stiffness). We also investigated the pressure effect of AuxPd1-xTe2 superconductors, in which Pd sites are substituted with Au, for three compositions. Our results suggest that the pressure dependence of Tc depends on the Debye temperature, which is similar to PdTe2.

Free Research Field

高圧固体物性

Academic Significance and Societal Importance of the Research Achievements

本課題研究の対象物質PdTe2は非自明な表面状態と超伝導状態を併せもつ。その点がトポロジカル超伝導の候補物質として注目される所以であり，本物質の超伝導物性に関する知見は当該分野に対し有益な情報となり得る。また，高圧力の利用は超伝導物性研究の分野でも用いられているが，本研究においてもその有効性を示すことができた。また，申請者の特徴は特に構造的な観点も重視して物性の理解に努める点であり，本課題はその利点がよく表れた成果といえる。