Constraining the Superconducting Gap of Monolayer FeSe/SrTiO3 via Statistical Analysis and Tip-Height-Dependent Tunneling Spectroscopy
Abstract
Monolayer FeSe grown on SrTiO3 (001) exemplifies interface-enhanced superconductivity, exhibiting a transition temperature nearly ten times that of bulk FeSe. Yet, its tunneling spectra lack clearly identifiable superconducting coherence peaks, preventing an unambiguous determination of the gap magnitude. Here, we use ultralow-temperature scanning tunneling spectroscopy as a function of temperature, tip-sample separation, and lateral position to disentangle tunneling contributions by statistical analysis. Decay rates extracted by regression of tip-height-dependent spectroscopy reveal three energy regimes: Andreev-reflection-dominated tunneling below 6 meV, mixed Andreev and quasiparticle tunneling between 6 and 13 meV, and predominantly quasiparticle tunneling above 13 meV. Spatially resolved spectroscopy and correlation analysis further reveal that the tunneling conductance is predominantly localized near defects below 6 meV but becomes spatially extended at higher energies. Together, these results constrain the superconducting gap to lie between 6 and 13 meV. Our findings establish statistical analysis of spectroscopy as a powerful approach to constraining superconducting gap structures when complex spectral features prevent the unambiguous identification of coherence peaks.
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BibTeX
@misc{shin2026constraining,
title = {{Constraining the Superconducting Gap of Monolayer FeSe/SrTiO$_3$ via Statistical Analysis and Tip-Height-Dependent Tunneling Spectroscopy}},
author = {Dongwon Shin and Xiyou Peng and Kaleb McClure and Paolo Vilmercati and Chris Howard and Petro Maksymovych and Norman Mannella and Hanno H. Weitering and Wonhee Ko},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.03978},
eprint = {2611.03978},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.03978},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Constraining the Superconducting Gap of Monolayer FeSe/SrTiO_3 via Statistical Analysis and Tip-Height-Dependent Tunneling Spectroscopy
AU - Dongwon Shin
AU - Xiyou Peng
AU - Kaleb McClure
AU - Paolo Vilmercati
AU - Chris Howard
AU - Petro Maksymovych
AU - Norman Mannella
AU - Hanno H. Weitering
AU - Wonhee Ko
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.03978
UR - https://arxiv.org/abs/2611.03978
AB - Monolayer FeSe grown on SrTiO_3 (001) exemplifies interface-enhanced superconductivity, exhibiting a transition temperature nearly ten times that of bulk FeSe. Yet, its tunneling spectra lack clearly identifiable superconducting coherence peaks, preventing an unambiguous determination of the gap magnitude. Here, we use ultralow-temperature scanning tunneling spectroscopy as a function of temperature, tip-sample separation, and lateral position to disentangle tunneling contributions by statistical analysis. Decay rates extracted by regression of tip-height-dependent spectroscopy reveal three energy regimes: Andreev-reflection-dominated tunneling below 6 meV, mixed Andreev and quasiparticle tunneling between 6 and 13 meV, and predominantly quasiparticle tunneling above 13 meV. Spatially resolved spectroscopy and correlation analysis further reveal that the tunneling conductance is predominantly localized near defects below 6 meV but becomes spatially extended at higher energies. Together, these results constrain the superconducting gap to lie between 6 and 13 meV. Our findings establish statistical analysis of spectroscopy as a powerful approach to constraining superconducting gap structures when complex spectral features prevent the unambiguous identification of coherence peaks.
ER -