Electron-Phonon Mass Enhancement in Multi-Layers

TL;DR

This paper investigates how electron-phonon mass enhancement varies in multi-layered metals, revealing homogeneous, anisotropic, and bulk behaviors depending on layer thickness, which could enable tailored electronic properties.

Contribution

It demonstrates the manipulation of electron-phonon mass enhancement in multi-layer structures with varying thicknesses, showing complex behavior beyond bulk properties.

Findings

Homogeneous enhancement in thin layers

Anisotropic and position-dependent enhancement in intermediate layers

Bulk behavior in thick layers

Abstract

A strong electron-phonon interaction in a metal increases the electron density of states in the vicinity of the Fermi energy dramatically. This phenomenon is called electron-phonon mass enhancement. In this paper the question is investigated whether the mass enhancement can be manipulated in multi-layers of two metals with strong and weak electron-phonon interaction. A rich behavior is observed for different thickness ranges of the layers. For thin layers one observes a rather homogeneous averaged enhancement. However, for an intermediate thickness range the mass enhancement is highly anisotropic, i.e. direction dependent, as well as position dependent. For large layer thicknesses one obtains the bulk behavior for each metal.