Long-range magnetic order with disordered spin orientations in a high-entropy antiferromagnet

TL;DR

This study reveals a rare case where a high-entropy antiferromagnet maintains long-range magnetic order despite atomic disorder, with element-specific spin orientations influenced by competing anisotropies and interactions.

Contribution

It demonstrates the existence of long-range magnetic order with disordered spin orientations in a high-entropy magnetic material, elucidating the microscopic mechanisms involved.

Findings

Long-range zigzag antiferromagnetic order observed below 72 K

All four transition-metal elements participate in the magnetic transition

Distinct spin orientations for different elements due to competing anisotropies

Abstract

Disorder in magnetic systems typically suppresses long-range order, promoting short-range states such as spin glasses and magnetic clusters. This is particularly prominent in high-entropy materials, characterized by the random distributions of local magnetic entities and exchange interactions. However, in rare exceptions, long-range magnetic order can persist in high-entropy systems, while the microscopic characters and underlying mechanisms remain elusive, especially the magnetic behaviors of individual elements. Here, combining neutron diffraction and resonant soft x-ray scattering, we have conducted an element-specific investigation into the magnetic order of a high-entropy honeycomb-lattice van der Waals material (Mn1/4Fe1/4Co1/4Ni1/4)PS3. Despite significant atomic disorder, long-range zigzag antiferromagnetic order is observed below 72 K, with all four transition-metal elements participating in a unified phase transition. However, the spin orientations of various elements are distinct, attributed to the competition between single-ion anisotropies and exchange interactions. Our findings showcase a novel form of long-range magnetic order with disordered spin orientations, which is synergically stabilized by distinct magnetic elements in a high entropy magnet, offering a new paradigm for understanding complex magnetic systems.