The Evolution of Co₂MnGa Topological Magnetic Nanoparticles

Magnetic nanoparticles exhibit electronic structure properties that are applicable in biomedicine, optical sensing, and energy harvesting. Heusler compounds are ideal materials for nanoparticles due to their tunability, topological properties, and structural stability. Co₂MnGa, a recently discovered cubic Heusler, shows a unique topological electronic structure with Weyl nodes that increase and stabilize dissipationless transport properties needed for many applications. We use first principles calculations to compare a series of bulk materials with electronic structures ranging from topological to half-metallic, including Fe, Co₂MnGa, Fe₃O₄, and CrPt₃, to small nanoparticles (<25 nm³). We find the size of the nanoparticle strongly determines the Curie temperature and the Weyl topology still has influence on the nanoparticles. We see that the magnetic texture oscillates in the nanoparticle due to the new boundary conditions. These results allow for atomistic control of magnetization and the spin of electrons in nanoparticles needed for the aforementioned applications.