Quantum Well Electronic States in Spatially Decoupled 2D Pb Nanoislands on Nb-doped SrTiO3(001)

TL;DR

This study investigates the quantum well electronic states of isolated 2D Pb nanoislands on Nb-doped SrTiO3(001), revealing unique quantum confinement effects and scattering properties that differ from other substrates, with implications for nanoscale superconductivity.

Contribution

It provides the first detailed analysis of quantum well states and scattering phase shifts of Pb nanoislands on Nb-doped SrTiO3(001), highlighting their unique electronic properties.

Findings

No wetting layer forms, leading to isolated nanoislands.

Extracted quantum parameters: vg = 1.804 m/s, kF = 1.575 Å^{-1}.

Identified metallic-like scattering interface similar to Pb/Ag(111).

Abstract

Two-dimensional (2D) Pb nanoisland has established an ideal platform for studying the quantum size effects on growth mechanism, electronic structures as well as high-temperature superconductivity. Here, we investigate the growth and quantum well electronic states of the 2D Pb nanoisland on Nb-doped SrTiO3(001) by scanning tunneling microscopy and spectroscopy. In contrast to Pb/Si(111), Pb/Cu(111) and Pb/Ag(111), there is no wetting layer of Pb formed on Nb-doped SrTiO3(001) surface, resulting in isolated Pb nanoislands with an apparent height of 4 atomic layers as the building blocks for the island growth. According to the thickness-dependent quantum well states resolved in both occupied and unoccupied energy regions, the constant group velocity vg = 1.804+-0.106 m/s and Fermi wavevector kF = 1.575 {\AA}-1, have been extracted from a linear fit of the Pb(111) band dipersion along the {\Gamma}-L direction. In addition, the energy-dependent scattering phase shift {\phi}(E) obtained by means of phase accumulation model shows a metallic-like scattering interface analogous to Pb/Ag(111). These spatially decoupled 2D Pb nanoislands thus realize an opportunity to explore the intrinic quantum confinement phenomena in nanoscale superconductors on the doped titanium-oxide-type substrate.