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MA: Fachverband Magnetismus
MA 1: Computational Magnetism I
MA 1.3: Vortrag
Montag, 16. März 2020, 10:00–10:15, HSZ 04
Impact of the magnetic structure on the phase stability and functional properties of binary and ternary Mn alloys — •Ingo Opahle, Nuno Fortunato, Harish K. Singh, Qiang Gao, Oliver Gutfleisch, and Hongbin Zhang — Institute of Materials Science, TU Darmstadt, 64287 Darmstadt, Germany
Mn alloys are of interest for hard magnetic, magnetocaloric and spintronics applications. The magnetic structure of Mn alloys can be complex, which makes computational high-throughput predictions of novel Mn based functional materials highly demanding.
We use high-throughput density functional calculations to determine the magnetic ground state of known compounds in several binary and ternary Mn alloy systems. Initial spin structures are obtained by algorithms based on maximal magnetic subgroups and antiferromagnetic coupling of sublattices. We show that the magnetic structure can have a strong impact on the calculated phase stability. For binary alloys of Mn with Ir, Pt and Au the formation energy for the ground state is up to 250 meV/atom lower compared to calculations with an assumed ferromagnetic structure. Phase diagrams assuming a ferromagnetic structure are unreliable for these systems and can not be used to identify important magnetic materials like Mn3Ir used in exchange biased films for data storage or the spin-orbit-torque compound Mn2Au.
Based on the magnetic ground state phase diagrams we performed structure type searches and discuss potentially new stable binary phases. Further, the impact of the magnetic structure on functional properties of Mn alloys is illustrated at hand of a few examples.