QuTech and Kavli Institute of Nanoscience , Delft University of Technology , 2600 GA Delft , The Netherlands.
AGH University of Science and Technology , Academic Centre for Materials and Nanotechnology , al. A. Mickiewicza 30 , 30-059 Krakow , Poland.
Nano Lett. 2018 Oct 10;18(10):6483-6488. doi: 10.1021/acs.nanolett.8b02981. Epub 2018 Sep 21.
Low dimensional semiconducting structures with strong spin-orbit interaction (SOI) and induced superconductivity attracted great interest in the search for topological superconductors. Both the strong SOI and hard superconducting gap are directly related to the topological protection of the predicted Majorana bound states. Here we explore the one-dimensional hole gas in germanium silicon (Ge-Si) core-shell nanowires (NWs) as a new material candidate for creating a topological superconductor. Fitting multiple Andreev reflection measurements shows that the NW has two transport channels only, underlining its one-dimensionality. Furthermore, we find anisotropy of the Landé g-factor that, combined with band structure calculations, provides us qualitative evidence for the direct Rashba SOI and a strong orbital effect of the magnetic field. Finally, a hard superconducting gap is found in the tunneling regime and the open regime, where we use the Kondo peak as a new tool to gauge the quality of the superconducting gap.
具有强自旋轨道相互作用 (SOI) 和诱导超导性的低维半导体结构引起了人们对拓扑超导体的极大兴趣。强 SOI 和硬超导能隙都直接与预测的马约拉纳束缚态的拓扑保护有关。在这里，我们探索了锗硅 (Ge-Si) 核壳纳米线 (NW) 中的一维空穴气体，作为创造拓扑超导体的新材料候选。拟合多个安德烈夫反射测量结果表明，该 NW 只有两个传输通道，突出了其一维性。此外，我们发现朗德 g 因子的各向异性，结合能带结构计算，为我们提供了直接 Rashba SOI 和磁场强轨道效应的定性证据。最后，在隧道和开放区域中发现了硬超导能隙，我们使用近藤峰作为衡量超导能隙质量的新工具。
