Uncovering electron scattering mechanisms in NiFeCoCrMn derived concentrated solid solution and high entropy alloys

TL;DR

This study investigates how disorder affects electron transport in NiFeCoCrMn high entropy alloys, revealing that spin-dependent scattering and electron filling influence resistivity and mean-free-path variations.

Contribution

It provides a detailed ab-initio analysis of electron scattering mechanisms in high entropy alloys, highlighting the role of spin channels and disorder types in transport properties.

Findings

Carrier density remains high across alloys.

Mean-free-path varies from ~10 Å to ~1000 Å.

Spin-dependent disorder dominates scattering mechanisms.

Abstract

Whilst it has long been known that disorder profoundly affects transport properties, recent measurements on a series of solid solution 3d-transition metal alloys reveal two orders of magnitude variations in the residual resistivity. Using ab-initio methods, we demonstrate that, while the carrier density of all alloys is as high as in normal metals, the electron mean-free-path can vary from ~10 {\AA} (strong scattering limit) to ~10$^3$ {\AA} (weak scattering limit). Here, we delineate the underlying electron scattering mechanisms responsible for this disparate behavior. While spin dependent site-diagonal disorder is always dominant, for alloys containing only Fe, Co, and Ni the majority spin channel experiences negligible disorder scattering, thereby providing a short circuit, while for Cr/Mn containing alloys both spin channels experience strong disorder scattering due to an electron filling effect. Unexpectedly, other scattering mechanisms (e.g. displacement scattering) are found to be relatively weak in most cases.