Superconductivity near the saddle point in the two-dimensional Rashba system Si(111)- 3 × 3 -(Tl,Pb)

T. MacHida, Y. Yoshimura, T. Nakamura, Y. Kohsaka, T. Hanaguri, C. R. Hsing, C. M. Wei, Y. Hasegawa, S. Hasegawa, A. Takayama

研究成果: Article査読


Two-dimensional Rashba superconductor Si(111)-3×3-(Tl,Pb) is a candidate platform of mixed spin-singlet and -triplet superconductivity. A recent scanning tunneling microscope (STM) experiment revealed a pseudogap at the vortex core, suggesting the finite triplet component [Nakamura, Phys. Rev. B 98, 134505 (2018)2469-995010.1103/PhysRevB.98.134505]. Detailed spectroscopic information of the superconducting gap and the low-energy band structure is necessary to establish the putative triplet superconductivity. Here, we performed high-energy-resolution spectroscopic imaging experiments on Si(111)-3×3-(Tl,Pb) using an ultralow temperature STM. We found that various spectroscopic features, including the vortex-core spectrum, are consistent with spin-singlet s-wave superconductivity, having no sign of the triplet component. The apparent contradiction with the previous STM result suggests that the nature of superconductivity changes within the same system. From the analysis of the quasiparticle interference patterns, we found that the Fermi energy is in the close vicinity of the saddle point near the M¯ point. We speculate that the nature of superconductivity varies depending on the saddle-point energy with respect to the Fermi energy, which is sample-dependent due to different band filling.

ジャーナルPhysical Review B
出版ステータスPublished - 2022 2月 1

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学


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