Zero-bias anomaly in nano-scale hole-doped Mott insulators on a triangular silicon surface

Abstract

Adsorption of 1/3 monolayer of Sn on a heavily-doped p-type Si(111) substrate results in the formation of a hole-doped Mott insulator, with electronic properties that are remarkably similar to those of the high-Tc copper oxide compounds. In this work, we show that the maximum hole-density of this system increases with decreasing domain size as the area of the Mott insulating domains approaches the nanoscale regime. Concomitantly, scanning tunneling spectroscopy data at 4.4 K reveal an increasingly prominent zero bias anomaly (ZBA). We consider two different scenarios as potential mechanisms for this ZBA: chiral d_(x^2 -y^2 )+ id_xy wave superconductivity and a dynamical Coulomb blockade (DCB) effect. The latter arises due to the formation of a resistive depletion layer between the nano-domains and the substrate. Both models fit the tunneling spectra with weaker ZBAs, while the DCB model clearly fits better to spectra recorded at higher temperatures or from the smallest domains with the strongest ZBA. Consistently, STS spectra from the lightly-doped substrates display oscillatory behavior that can be attributed to conventional Coulomb staircase behavior, which becomes stronger for smaller sized domains. We conclude that the ZBA is predominantly due to a DCB effect, while a superconducting instability is absent or a minor contributing factor.

References in corpus (8)

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Cited by in corpus (11)

• Tomonaga-Luttinger liquid in the edge channels of a quantum spin Hall insulator
• Evidence for chiral superconductivity on a silicon surface
• Superconductivity in a hole-doped Mott-insulating triangular adatom layer on a silicon surface
• Design and realization of topological Dirac fermions on a triangular lattice
• Chiral d-wave Superconductivity in a Triangular Surface Lattice Mediated by Long-range Interaction
• Experimental observation of pseudogap in a modulation-doped Mott insulator: Sn/Si(111)-($\sqrt{3}\times \sqrt{3}$)-R30${}^{\text{o}}$
• Magnetism and superconductivity in doped triangular-lattice Mott insulators
• Alloying 2D VSe2 with Pt: from a charge density wave state to a disordered insulator
• Electronic structure, spin-orbit interaction and electron-phonon coupling of triangular adatom lattices on semiconductor substrates
• Signatures of the order parameter of a superconducting adatom layer in magnetic field dependent quasiparticle interference
• The electronic structure of a doped Mott-Hubbard surface