Mechanism of charge transfer and electrostatic field fluctuations in high entropy metallic alloys

TL;DR

This paper introduces a minimal model for understanding charge transfer and electrostatic fluctuations in high entropy alloys, revealing how disorder influences electronic properties and offering insights for improved disorder modeling techniques.

Contribution

The work develops a perturbative theoretical framework capturing disorder-driven charge and field fluctuations in disordered metals, applicable to high entropy alloys and beyond.

Findings

Reproduces linear charge transfer trends in alloys

Elucidates microscopic origins of charge fluctuations

Suggests systematic corrections for first-principles disorder models

Abstract

High entropy alloys present a new class of disordered metals which hold promising prospects for the next generation of materials and technology. However, much of the basic physics underlying these robust, multifunctional materials -- and those of other, more generic forms of disordered matter -- still remain the subject of ongoing inquiry. We thus present a minimal-working model that describes the disorder-driven fluctuations in the electronic charge distributions and electrostatic "Madelung" fields in disordered metals. Our theory follows a standard perturbative scheme and captures the leading contributions from dominant electronic processes, including electrostatic screening and impurity scattering events. We show here that a modest first-order treatment incorporating these effects is sufficient to reproduce the linear charge transfer trends featured in both high-entropy and other conventional alloys, our model also shedding light on the microscopic origins of these statistical features. We further elaborate on the nature of these electronic charge and Madelung field fluctuations by determining how these emerge from the statistics of the underlying disorder, and how these can be described using the linear response formulation that we develop here. In doing so, our work answers various questions which have long-perplexed the disordered materials community. It also opens up possible avenues for providing systematic corrections to modern first-principles approaches to disorder-modeling (e.g. the conventional CPA method) which currently lack these statistical features.