To our knowledge, no magnetic B2 phase in the Al-Mn system of near-equiatomic compositions
has been reported so far. Here, we investigate the structural and magnetic characteristics
of Al45Mn41.8X13.2 (X = Fe, Co or Ni) alloys. We demonstrate that adding 13.2 atomic
percent magnetic 3d metal to AlMn stabilizes a ferromagnetic B2 structure, where Al
and X occupy different sublattices. We employ density functional theory calculations
and experimental characterizations to underscore the role of the late 3d metals for
the phase stability of the quasi-ordered ternary systems. We show that these alloys
possess large local magnetic moments primarily due to Mn atoms partitioned to the
Al-free sublattice. The revealed magneto-chemical effect opens alternative routes
for tailoring the magnetic properties of B2 intermetallic compounds for various magnetic
applications.
