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arXiv · 2210.08615

Theoretical antiferromagnetism of ordered face-centered cubic Cr-Ni alloys

Flynn Walsh·Robert O. Ritchie·Mark Asta
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Abstract

Contrary to prior calculations, the Ni-rich ordered structures of the Cr-Ni alloy system are found to be antiferromagnetic under semi-local density-functional theory. The optimization of local magnetic moments significantly increases the driving force for the formation of CrNi$_2$, the only experimentally observed intermetallic phase. This structure's ab initio magnetism appears well described by a Heisenberg Hamiltonian with longitudinal spin fluctuations; itinerant Cr moments are induced only by the strength of exchange interactions. The role of magnetism at temperature is less clear and several scenarios are considered based on a review of experimental literature, specifically a failure of the theory, the existence of an overlooked magnetic phase transition, and the coupling of antiferromagnetism to chemical ordering. Implications for related commercial and high-entropy alloys are discussed for each case.

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Flynn Walsh, Robert O. Ritchie, Mark Asta. 2022-10-16. Theoretical antiferromagnetism of ordered face-centered cubic Cr-Ni alloys. https://doi.org/10.1103/physrevmaterials.6.113602

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