Surface Polaron Formation in the Holstein model

TL;DR

This paper investigates how a solid-vacuum interface influences polaron formation in a strongly coupled electron-phonon system, revealing surface effects that facilitate polaron formation compared to the bulk.

Contribution

It provides a detailed analysis of surface versus bulk polaron formation in the Holstein model using dynamical mean-field theory, highlighting surface facilitation of polaron formation.

Findings

Polaron formation occurs more easily at the surface than in the bulk.

The metal-insulator transition occurs at a unique critical coupling in both surface and bulk.

Surface effects modify the electron-phonon interaction dynamics.

Abstract

The effect of a solid-vacuum interface on the properties of a strongly coupled electron-phonon system is analyzed using dynamical mean-field theory to solve the Holstein model in a semi-infinite cubic lattice. Polaron formation is found to occur more easily (i.e., for a weaker electron-phonon coupling) on the surface than in the bulk. On the other hand, the metal-insulator transition associated to the binding of polarons takes place at a unique critical strength in the bulk and at the surface.