Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 7: Focus Session: Magnetism in Materials Science: Thermodynamics, Kinetics and Defects I (joint session MM/MA)
MA 7.2: Vortrag
Montag, 12. März 2018, 10:45–11:00, TC 010
Continuous transition from antiferro- to ferromagnetic state via moment canting in Ni2−xCoxMnAl — •Michael Leitner1, Pascal Neibecker1, Matthias Opel2, Xiao Xu3, Ryosuke Kainuma3, and Winfried Petry1 — 1Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching — 2Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching — 3Department of Materials Science, Tohoku University, Sendai 980-8579, Japan
The magnetic structure of materials is often discussed only in terms of the classical concepts of ferromagnetism and antiferromagnetism, however, interesting phenomena can be expected when a system is driven to the boundary between these regimes by adjusting external parameters. B2-ordered Ni2−xCoxMnAl is a case in point: Ni2MnAl, a potential ferromagnetic shape-memory material, displays antiferromagnetism [1], while NiCoMnAl, predicted to be a halfmetal, is ferromagnetic [2].
We have studied this system for 0≤ x≤ 0.8. Temperature-dependent neutron powder diffraction proves an antiferromagnetic ordering for x<0.4, while the macroscopic magnetization shows an increasing longitudinal component for all x>0. We argue that this constitutes a continuous, spatially homogeneous transition from antiferro- to ferromagnetism via canted spins, which is reproduced by a simple Heisenberg model.
[1] M. Acet et al., J. Appl. Phys. 92, 3867 (2002)
[2] P. Neibecker et al., Phys. Rev. B 96, 165131 (2017)