DPG Phi
Verhandlungen
Verhandlungen
DPG

Berlin 2015 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 49: POSTER II

MA 49.30: Poster

Donnerstag, 19. März 2015, 15:00–18:00, Poster A

Order-disorder transitions in Co2FeAl0.5Si0.5 probed via in-situ neutron diffraction — •Ahmad Omar1, Matthias Frontzek2, Alexey Alfonsov1,3, Bernd Büchner1,4, and Sabine Wurmehl1,41IFW Dresden, 01069, Germany — 2Paul Scherrer Institute, 5232 Villigen, Switzerland — 3Molecular Photoscience Research Center, Kobe University, Kobe 657-8501, Japan — 4Institut für Festkörperphysik, TU Dresden, 01062, Germany

The Co2FeAl0.5Si0.5 Heusler compound is predicted to be a half-metallic ferromagnet in the ordered L21 structure [1], and a high TMR ratio has been reported [2]. Heusler compounds are prone to anti-site disorders which strongly affect the physical properties. It is thus pertinent to understand the existential regimes of different disorders and order-disorder transitions. Here we present neutron diffraction measurements performed in-situ during annealing of powder samples. We have also measured pre-annealed powder samples at room temperature to compare the effect of annealing. We do not observe any sharp transition between the L21-B2 and B2-A2 disorders, which is in contrast to literature [3]. The transitions seem to be predominantly entropy-driven, although the TCurie and the transition temperature seem coupled. Also, zero-field NMR on powder with alternate annealing, as per neutron data, shows a higher L21 ordering. In summary, we gain an understanding of the order-disorder transitions and propose an alternate annealing for improved ordering. Ref.: [1] Fecher et al. J. Phys. D: Appl. Phys. 40 (2007) 1582-1586 [2] Tezuka et al. Appl. Phys. Lett. 94 (2009) 162504 [3] Balke et al. Appl. Phys. Lett. 90 (2007) 242503

100% | Mobil-Ansicht | English Version | Kontakt/Impressum/Datenschutz
DPG-Physik > DPG-Verhandlungen > 2015 > Berlin