Reversible phase transformation and doubly-charged anions at the surface of simple cubic RbC60

TL;DR

This study investigates the surface electronic properties of simple cubic RbC60 thin films, revealing reversible phase transitions, strongly-correlated metallic behavior, and the presence of doubly-charged C602- anions at the surface.

Contribution

It provides new insights into the surface phase behavior and electronic structure of RbC60, highlighting the role of surface charge states and correlations.

Findings

Reversible simple cubic-to-dimer transition at the surface

Observation of a sharp Fermi edge indicating metallicity

Identification of C602- anions contributing to the Fermi level

Abstract

The simple cubic phase of a RbC60 thin film has been studied using photoelectron spectroscopy. The simple cubic-to-dimer transition is found to be reversible at the film surface. A sharp Fermi edge is observed and a lower limit of 0.5 eV is found for the surface Hubbard U, pointing to a strongly-correlated metallic character of thin-film simple cubic RbC60. A molecular charge state is identified in the valence band and core level photoemission spectra which arises from C602- anions and contributes to the spectral intensity at the Fermi level.