We discovered a new hexagonal metallic antiferromagnetic phase in the Cu-Mn-As system. Electrical switching and read-out of tetragonal CuMnAs inspired a world-wide research effort in metallic antiferromagnets. Phase equilibria in this system (Fig. a) however is poorly understood.
We synthesized crystals of hexagonal Cu0.8Mn1.2As and determined their chemical (Fig. b) and magnetic structure (Fig. c) through X-ray and neutron scattering supported by first principles density functional theory. No previously-known material of any composition has the same arrangement of atoms, so our work creates new possibilities for designing and engineering materials.
Conclusion: The discovery of new metallic antiferromagnetic phases advances fundamental understanding of this important new class of materials.