Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 13: Magnetic Heuslers and Semiconductors
MA 13.1: Talk
Monday, March 9, 2026, 15:00–15:15, POT/0361
Investigation on the interplay of antisite disorder and magnetic ordering in Co2FeAl1−xSix Heusler system — •Ahmad Omar1, Matthias Frontzek2, Robin Kramer1, Bernd Büchner1, and Sabine Wurmehl1 — 1Leibniz Institute for Solid State and Materials Research Dresden, Germany — 2PSI Villigen, Switzerland
Quaternary Co-based Heusler compounds such as Co2FeAl1−xSix system are predicted to demonstrate half-metallic ferromagnetism for the L21 ordered structure. However, the observed physical properties, are often in contrast to theory due to antisite disorder commonly present in practical samples. The L21- B2 order-disorder transition is further convoluted with the ferromagnetic transition and is not well understood. Therefore, it is pertinent to understand the ordering phenomenon and develop routes to improve the order for practical realization of the desired properties. Herein, we present a systematic study of the impact of synthesis route and annealing parameters on the obtained order fraction in the samples, through detailed structural and magnetic characterization. In-situ neutron diffraction is performed during annealing to directly investigate the order-disorder transition. The interplay of disorder and the magnetic ordering is further studied through magnetic field annealing experiments. We aim to elucidate the structure-property relationships in the quaternary Co2FeAl1−xSix system, developing methodology for tuning of the disorder through synthesis or post-processing routes, thus enabling a practical realization of half metallic ferromagnetism in the Heusler system.
Keywords: Co-based Heusler; Order-disorder transition; Neutron diffraction; Annealing