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X-ORIGINAL-URL:https://www.lps.u-psud.fr/
X-WR-CALNAME:Laboratoire de physique des Solides
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BEGIN:VEVENT
CLASS:PUBLIC
DTSTART;TZID=Europe/Paris:20260618T150000
DTEND;TZID=Europe/Paris:20260618T180000
DTSTAMP:20260616T081700
UID:MEC-955d864a62659945cc9434898e275deb@lps.u-psud.fr
CREATED:20260616
LAST-MODIFIED:20260616
PRIORITY:5
TRANSP:OPAQUE
SUMMARY:Hanno Weitering : Hotspot nesting and intertwined density wave order near a van Hove singularity in the chiral d-wave superconductor Sn/Si(111)
DESCRIPTION:\nThe emergence of unconventional superconductivity from a landscape of competing electronic instabilities remains a central problem in condensed-matter physics. Sn/Si(111), a superconducting triangular-lattice surface system with strong electronic correlations and a nearby van Hove singularity, provides a promising platform for exploring this interplay. Recent evidence for chiral d-wave pairing1,2 further places the system among a small class of candidate topological superconductors.\n\n\n\nIn this talk, I will present a doping-dependent study of the phase diagram of Sn/Si(111). At low doping levels, the system phase-separates into lightly doped and heavily doped regions. The lightly doped regime exhibits an intertwined phase in which chiral d-wave superconductivity coexists with density-wave order. Scanning tunneling spectroscopy reveals two superconductivity-induced energy scales, with coherence peaks at approximately ±2.2 meV and ±4.2 meV. Conductance maps acquired between these energies display a 2×2 modulation consistent with either charge-density-wave order or a triple-Q spin-density-wave state. The emergence of this order correlates with the proximity of a van Hove singularity at the M point to the Fermi level and is consistent with hotspot nesting of the M-point states. The simultaneous disappearance of both spectral features at the superconducting transition temperature, together with an enhanced superconducting energy scale inferred from in-gap bound states, supports a scenario of intertwined superconductivity and density-wave order.\n\n\n\nThese results reveal a previously unexplored low-doping regime of Sn/Si(111), where electronic reconstruction driven by the M-point van Hove singularity gives rise to competing and cooperative many-body orders. The findings establish Sn/Si(111) as a model platform for investigating the relationship between topology, strong correlations, and unconventional superconductivity on a triangular lattice.1 X. Wu et al., Phys. Rev. X 16, 011026 (2026).2 F. Ming et al., Nature Phys. 19, 500-506 (2023)\n
URL:https://www.lps.u-psud.fr/events/hanno-weitering-hotspot-nesting-and-intertwined-density-wave-order-near-a-van-hove-singularity-in-the-chiral-d-wave-superconductor-sn-si111/
CATEGORIES:Séminaire Matière Quantique (SMQ),Séminaires
LOCATION:Orsay
ATTACH;FMTTYPE=image/jpeg:https://www.lps.u-psud.fr/wp-content/uploads/2026/06/hanno-weitering.jpg
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