The Nature of Surface States on Vicinal Cu (775): An STM and Photoemission Study

TL;DR

This study combines ARPES and STM techniques to analyze surface states on vicinal Cu(775), revealing step-modulated and terrace-modulated states, and determining the terrace width at which the surface state transitions between these modulations.

Contribution

It provides a detailed experimental analysis of surface states on Cu(775), identifying the transition point between step and terrace modulation states using combined ARPES and STM data.

Findings

Surface states are predominantly step-modulated on Cu(775).

A weak terrace-modulated state is observed, linked to larger terrace widths.

The terrace width at which the surface state switches modulation types is quantified.

Abstract

We report ARPES and a set of in situ STM measurements on a narrow-terrace-width vicinal Cu(111) crystal surface, Cu(775), whose vicinal cut lies close to the transition between terrace and step modulation. These measurements show sharp zone-folding (or Umklapp) features with a periodicity in k||, indicating that the predominant reference plane is that of Cu(775), i.e. that the surface is predominately step-modulated. Our measurements also show variation in Umklapp intensity with photon energy, which is consistent with prior ARPES experiments on other vicinal Cu(111) surfaces and in agreement with our designation of the state as being step modulated. The measurements also show a weak terrace-modulated state, which, based on several characteristics, we attribute to the presence of terrace widths larger than the ideal terrace width. By measuring the intensity ratio of the two distinct surface-state modulations from PE and the terrace-width distribution from STM, we derive a value for the terrace width, at which the surface-state switches between the two modulations.