Infrared Spectroscopic Study of Phase Transisions in A1c60 Compounds (a=K,Rb,Cs)

TL;DR

This study uses infrared spectroscopy to investigate phase transitions in alkali-doped C60 compounds, revealing different behaviors in Rb, K, and Cs variants related to their conductive and insulating phases.

Contribution

It provides new insights into phase separation and transition behaviors in doped C60 compounds, especially highlighting differences among Rb, K, and Cs doped samples.

Findings

Rb1C60 and K1C60 transition from conducting to insulating phases at low temperatures

Phase separation into different compounds observed in K1C60 and Rb1C60

Cs1C60 exhibits similar low-temperature behavior to Rb1C60 upon slow cooling

Abstract

Optical measurements on doped C$_{60}$ films provide evidence for a transition from a high temperature conducting phase to a low temperature insulating phase in quenched Rb$_1$C$_{60}$ and K$_1$C$_{60}$ compounds, while Cs$_1$C$_{60}$ did not exhibit this behavior. For slow cooled samples our study confirms earlier results indicating phase separation of K$_1$C$_{60}$ to K$_3$C$_{60}$ and C$_{60}$, and the formation of a new Rb$_1$C$_{60}$ phase at low temperatures. Upon slow cooling Cs$_1$C$_{60}$ behaves similar to Rb$_1$C$_{60}$.