2025/07/15 by Catherine K. Badding, Eric A. Riesel, Ryan A. Murphy +7 · 1 voice
Materials Science · Physics and Astronomy · #Hydrogen Storage and Materials #Magnetic Properties of Alloys #Rare-earth and actinide compounds
paper · doi:10.1021/jacs.5c06874
openalex publication_date 2025/07/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Creating and understanding new permanent magnets requires an understanding of the impact of orbital angular momentum on coercivity. A simple approach to interrogating this relationship is by incorporating high Z (where Z is the atomic number) elements into binary compounds to maximize spin–orbit coupling. The Mn–Bi system is an appealing platform for these studies since it contains MnBi, a permanent magnet with a large coercive field. We previously identified a new compound in the Mn–Bi system, MnBi 2, but could not elucidate its magnetic properties ex situ due to its decomposition upon decompression. Here, we harnessed synchrotron X-ray magnetic circular dichroism to probe the magnetism of MnBi 2 at high pressure within a diamond anvil cell. Our results indicate that MnBi 2 exhibits ferromagnetic hysteresis at both 10 K and room temperature. Through calculations and experiments, we show that orbital angular momentum and spin–orbit coupling from Bi impart magnetic anisotropy in MnBi 2 . Comparing the Mn–Bi family of compounds, we consider the Bi p and d orbitals to explain the differences in magnetic behavior within the system. Collectively, these results validate leveraging high- Z elements in the synthesis of new hard permanent magnets.