Hybrid one-atomic-layer physics on semiconductor surfaces without space inversion symmetry

2019 Fiscal Year Final Research Report

• Project/Area Number: 16H03998
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: The University of Tokyo
• Principal Investigator: Masutomi Ryuichi 東京大学, 大学院理学系研究科(理学部), 助教 (00397027)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 低次元超伝導 / ラッシュバ効果

Outline of Final Research Achievements

We observed a sharp upturn in the measurements on the temperature dependence of the parallel upper critical field for multiple monolayer films with layer-dependent Rashba spin-orbit interactions. Using numerical calculations with the Bogoliubov-de Gennes equations, we found that it corresponds to a transition from a complex-stripe phase to a helical phase. Our findings not only provide experimental evidence supporting the existence of the complex-stripe phase and the helical phase, but also offer a new platform to study non-trivial superconductivity caused by symmetry breaking, including odd-parity pair-density-wave superconductivity and 2D topological superconductivity predicted for multilayer systems that are made up of the 2D Rashba superconductors.

Free Research Field

低次元物性物理学

Academic Significance and Societal Importance of the Research Achievements

本研究は強いスピン軌道相互作用をもつ鉛の単原子層から構成される二層系および三層系を用いて、超伝導秩序変数が実空間で変調する非従来型超伝導の存在を上部臨界磁場の測定から立証するものである。この研究成果は秩序変数の大きさと位相の両方が変調する複素ストライプ相や秩序変数の位相のみが変調するヘリカル相の存在を実験的に明らかにするだけに留まらず、空間反転対称性の破れにより引き起こされる非従来型超伝導を研究する新たな舞台を提供する。