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Inferring the pairing symmetry of the superconducting Sn/Si(111) via angle-resolved terahertz pump spectroscopy

Mattia Iannetti1,2,*, Tommaso Cea1, Cesare Tresca1,2, Lara Benfatto3, and Gianni Profeta1,2

  • *Contact author: mattiaiannetti@gmail.com
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Phys. Rev. B 113, 054502 – Published 2 February, 2026

DOI: https://doi.org/10.1103/p357-5pth

Abstract

Doping tin surface epitaxially grown on silicon, Sn/Si(111), with boron atoms yields the appearance of a superconducting (SC) phase below Tc∼4−9K. Even though the pairing mechanism remains unknown, experimental evidence of chiral d−wave superconductivity has been recently reported, thus ruling out a phonon-mediated pairing. Here, we study theoretically the SC phase of the doped Sn/Si(111) within a t−J model investigating different symmetries of the order parameter. We analyze the photoexcitation of the system by intense terahertz pulses and show that the polarization dependence of the induced current can distinguish between different symmetries of the SC gap, thus providing an experimental means to investigate the spectroscopic features of the Sn/Si(111), and possibly to many other systems, across the SC transition.

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23 February, 2026

Correction: The author order was incorrect and has been fixed, which necessitated a change in the affiliation setup.

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Phys. Rev. B 113, 054502– Published 2 February, 2026
  • Received 12 December 2023
  • Revised 15 December 2025
  • Accepted 14 January 2026
  • Corrected 23 February 2026
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