Anomalous Raman shift in the ternary fullerides with t1g states

TL;DR

This study investigates the Raman shift dependence on charge transfer in ternary fullerides, revealing an anomalous shift in t1g states that cannot be solely explained by charge transfer effects.

Contribution

It identifies an anomalous Raman shift in t1g fullerides and highlights the limitations of charge transfer explanations for these shifts.

Findings

Raman spectra are similar across all ternary fullerides studied.

A crossover point at the boundary of t1u and t1g bands affects Raman shift dependence.

Anomalous Raman shifts observed in t1g fullerides cannot be explained solely by charge transfer.

Abstract

Raman shift dependence of charge transfer is studied in the two fulleride families of AxBa3C60 (x=0,3; A=K,Rb) and KxSm2.75C60 (x=0,3.25). It is found that the Raman spectra are essentially identical to each other for all ternary fullerides, The results show a crossover point at the boundary of t1u and t1g bands for the Raman shift dependence of charge transfer. For the t1u fullerides, the Ag(2) pinch mode follows the characteristic shift of ~6.3cm-1 per elementary charge widely observed in KxC60. The two Ag modes in t1g fullerides show a complicated behavior. An anomalous Raman shift is observed in the t1g fullerides. This anomalous Raman shift of the two Ag modes could not be explained only by charge transfer.