Bulk and element specific magnetism of the medium and high entropy Cantor-Wu alloys

TL;DR

This study investigates the magnetic properties of medium and high entropy Cantor-Wu alloys using advanced spectroscopic and magnetometry techniques, revealing isotropic spin densities and element-specific magnetic behaviors influenced by alloy composition.

Contribution

It provides the first detailed element-specific magnetic characterization of medium and high entropy Cantor-Wu alloys, highlighting the effects of disorder and element substitution on magnetic moments.

Findings

Bulk spin densities are isotropic due to disorder scattering.

Cr moments are antiparallel to the total magnetic moment.

Discrepancies exist between surface and bulk magnetic moments.

Abstract

Magnetic Compton scattering, x-ray magnetic circular dichroism spectroscopy and bulk magnetometry measurements are performed on a set of medium (NiFeCo and NiFeCoCr) and high (NiFeCoCrPd and NiFeCoCrMn) entropy Cantor-Wu alloys. The bulk spin momentum densities determined by magnetic Compton scattering are remarkably isotropic, and this is a consequence of the smearing of the electronic structure by disorder scattering of the electron quasiparticles. Non-zero x-ray magnetic circular dichroism signals are observed for every element in every alloy indicating differences in the populations of the majority and minority spin states implying finite magnetic moments. When Cr is included in the solid solution, the Cr spin moment is unambiguously antiparallel to the total magnetic moment, while a vanishingly small magnetic moment is observed for Mn, despite calculations indicating a large moment. Some significant discrepancies are observed between the experimental bulk and surface magnetic moments. Despite the lack of quantitative agreement, the element specific surface magnetic moments seem to be qualitatively reasonable.