TY - JOUR
T1 - Superconductivity near the saddle point in the two-dimensional Rashba system Si(111)- 3 × 3 -(Tl,Pb)
AU - MacHida, T.
AU - Yoshimura, Y.
AU - Nakamura, T.
AU - Kohsaka, Y.
AU - Hanaguri, T.
AU - Hsing, C. R.
AU - Wei, C. M.
AU - Hasegawa, Y.
AU - Hasegawa, S.
AU - Takayama, A.
N1 - Funding Information:
This work was supported by CREST project (No. JPMJCR16F2) and PRESTO project (No. JPMJPR19L8) from Japan Science and Technology Agency and Grants-in-Aid for Scientific Research (JSPS-KAKENHI Grants No. 19H01843 and No. 20H00342). We appreciate T. Sato and K. Sugawara for providing us with the evaporation source of Pb. We also thank Y. Tsutusumi for valuable discussions.
Publisher Copyright:
© 2022 American Physical Society.
PY - 2022/2/1
Y1 - 2022/2/1
N2 - 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.
AB - 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.
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U2 - 10.1103/PhysRevB.105.064507
DO - 10.1103/PhysRevB.105.064507
M3 - Article
AN - SCOPUS:85125236243
SN - 2469-9950
VL - 105
JO - Physical Review B
JF - Physical Review B
IS - 6
M1 - 064507
ER -