# Structural origins of electronic conduction in amorphous copper-doped alumina

## TL;DR

This study uses ab initio modeling to explore how copper clustering and structural features in amorphous alumina influence electronic conduction, revealing the role of Cu concentration and connectivity.

## Contribution

It provides new insights into the structural origins of conduction in amorphous copper-doped alumina through detailed modeling and analysis of Cu clustering, electronic properties, and conduction pathways.

## Key findings

- Cu atoms tend to cluster in alumina.
- Higher Cu concentrations lead to metallization by filling the band gap.
- Conduction pathways depend explicitly on Cu connectivity.

## Abstract

We perform an {\it ab initio} modeling of amorphous copper-doped alumina (a-Al$_2$O$_3$:Cu), a prospective memory material based on resistance switching, and study the structural origin of electronic conduction in this material. We generate molecular dynamics based models of a-Al$_2$O$_3$:Cu at various Cu-concentrations and study the structural, electronic and vibrational properties as a function of Cu-concentration. Cu atoms show a strong tendency to cluster in the alumina host, and metallize the system by filling the band gap uniformly for higher Cu-concentrations. We also study thermal fluctuations of the HOMO-LUMO energy splitting and observe the time evolution of the size of the band gap, which can be expected to have an important impact on the conductivity. We perform a numerical computation of conduction pathways, and show its explicit dependence on Cu connectivity in the host. We present an analysis of ion dynamics and structural aspects of localization of classical normal modes in our models.