EXTENDED ABSTRACT: High-entropy alloys, referring to alloys that contain multiple principal elements in near-equal atomic ratios, can form a single-phase crystal with an incredible simple lattice, e.g., face-centered cubic (fcc) or body centered cubic (bcc). A question thus arises as to why these alloys could form the particular crystal structure, despite their chemical complexity. It has long been suspected that magnetism could play a vital role. However, the nature of the magnetic order in multicomponent high-entropy alloys, if any, has remained elusive. By using elastic and inelastic neutron scattering, we demonstrated conclusive evidence of antiferromagnetic order below ~80 K in a single-phase fcc CrMnFeCoNi high-entropy alloy, known as Cantor alloy. Detailed analyses revealed that the magnetic structure in CrMnFeCoNi can be described as γ-Mn-like, with the magnetic moments confined in alternating (001) planes and pointing toward the <111> direction. We also revealed strong spin fluctuations persisting to room temperature in the same alloy. With the aid of first-principles calculations, it was argued that the antiferromagnetic ordering and the strong spin fluctuations stabilized the fcc phase. The fcc phase is a favored crystal structure for structural applications, as it allows the activation of multiple deformation mechanisms, i.e., dislocations, stacking faults, deformation twinning, etc., which are essential for achieving a large work-hardening capability and ductility. In this regard, this study provides hints for the development of advanced materials with high performance.
Keywords：Advanced characterization; Neutron scattering; High-entropy alloy; Antiferromagnetism. 

REFERENCES:
[1] L. Zhu, H. He, M. Naeem, X. Sun, J. Qi, P. Liu, S. Harjo, K. Nakajima, B. Li, X.-L. Wang, Phys. Rev. Lett., 133(12), (2024) 126701.