Pseudodoping of Metallic Two-Dimensional Materials by The Supporting Substrates

TL;DR

This paper reveals that hybridization between metallic 2D materials and substrates can cause an apparent heavy doping effect, called pseudodoping, which significantly impacts electronic properties without large actual charge transfer.

Contribution

The study introduces the concept of pseudodoping, demonstrating how substrate hybridization causes apparent doping effects in 2D metals without substantial charge transfer, supported by calculations and experiments.

Findings

Hybridization leads to large apparent doping effects.

Pseudodoping causes non-linear energy shifts in spectra.

Pseudodoping influences electronic phase formation.

Abstract

We demonstrate how hybridization between a two-dimensional material and its substrate can lead to an apparent heavy doping, using the example of monolayer TaS$_2$ grown on Au(111). Combining $\textit{ab-initio}$ calculations, scanning tunneling spectroscopy experiments and a generic model, we show that strong changes in Fermi areas can arise with much smaller actual charge transfer. This mechanism, which we refer to as pseudodoping, is a generic effect for metallic two-dimensional materials which are either adsorbed to metallic substrates or embedded in vertical heterostructures. It explains the apparent heavy doping of TaS$_2$ on Au(111) observed in photoemission spectroscopy and spectroscopic signatures in scanning tunneling spectroscopy. Pseudodoping is associated with non-linear energy-dependent shifts of electronic spectra, which our scanning tunneling spectroscopy experiments reveal for clean and defective TaS$_2$ monolayer on Au(111). The influence of pseudodoping on the formation of charge ordered, magnetic, or superconducting states is analyzed.