Fermi surface of an important nano-sized metastable phase: Al$_3$Li

TL;DR

This study investigates the electronic structure and Fermi surface of nanoscale Al3Li precipitates within an aluminum matrix, revealing unique insights into their properties using positron affinity techniques.

Contribution

It provides the first direct experimental characterization of the Fermi surface of nanoscale Al3Li, a phase previously inaccessible with conventional methods.

Findings

Positron affinity enables direct probing of nanoscale Al3Li precipitates.

Comparison with band structure calculations confirms the unique Fermi surface.

The results offer insights into the material properties of Al-Li alloys.

Abstract

Nanoscale particles embedded in a metallic matrix are of considerable interest as a route towards identifying and tailoring material properties. We present a detailed investigation of the electronic structure, and in particular the Fermi surface, of a nanoscale phase ($L1_2$ Al$_3$Li) that has so far been inaccessible with conventional techniques, despite playing a key role in determining the favorable material properties of the alloy (Al\nobreakdash-9 at. %\nobreakdash-Li). The ordered precipitates only form within the stabilizing Al matrix and do not exist in the bulk; here, we take advantage of the strong positron affinity of Li to directly probe the Fermi surface of Al$_3$Li. Through comparison with band structure calculations, we demonstrate that the positron uniquely probes these precipitates, and present a 'tuned' Fermi surface for this elusive phase.