Electron Propagation in Orientationally Disordered Fullerides

TL;DR

This study investigates how orientational disorder in doped fullerides affects electronic states, revealing that near the Fermi energy, electrons behave as propagating Bloch-like states despite strong disorder scattering.

Contribution

It introduces a cluster-Bethe-lattice model to analyze electronic spectra in disordered fullerides and compares it with supercell calculations, providing insights into disorder effects on electronic structure.

Findings

Electronic states near the Fermi energy remain propagating despite disorder.

Mean free path of electrons is approximately 20 Angstroms.

Disorder-averaged virtual-crystal Hamiltonian effectively describes the system.

Abstract

We study the electronic spectrum for doped electronic states in the orientationally disordered M3C60 fullerides. Momentum-resolved Green's functions are calculated within a cluster-Bethe-lattice model, and compared with results from calculations on periodically repeated supercells containing quenched orientational disorder. Despite the relatively strong scattering from orientational fluctuations, the electronic states near the Fermi energy are well described by propagating states characterized by an effective Bloch wave vector, and a mean free path of approximately 20 Angstroms. The effective Fermi surface is calculated in this model. This differs from that previously calculated for the orientationally ordered crystal, but is relatively well described within a disorder-averaged virtual-crystal Hamiltonian, which we derive.