Phase Separation and Charge Transfer in a K-doped C60 Monolayer on Ag(001)

TL;DR

This study investigates how potassium doping affects the phase separation and charge transfer in C60 monolayers on Ag(001), revealing distinct phases with varying electron doping levels and an anomalously high doping in one phase.

Contribution

It provides detailed STM and spectroscopy analysis of phase separation and charge transfer in K-doped C60 monolayers, highlighting new doping behaviors and phase distinctions.

Findings

Formation of two well-ordered KxC60 phases with different charge transfer levels

High-temperature annealing distills a K-free C60 phase from doped phases

Observation of an anomalously large electron-doping level in the higher doped phase

Abstract

We have performed a scanning tunneling microscopy and spectroscopy study of potassium-doped C60 monolayers (KxC60) on Ag(001) in the regime of x ~ 1. Low temperature annealing (640 K) leads to the formation of two well-ordered KxC60 phases that exhibit differing levels of electron charge transfer. Further annealing (710 K) distills out the higher electron-doped phase from the lower electron-doped phase, leaving behind a third C60 phase completely devoid of K. Spectroscopic measurements indicate that the electron-doping level of the higher electron-doped KC60 phase is anomalously large.