Magnetic structure of Fe{sub 1-x}Co{sub x}Si in a magnetic field studied via small-angle polarized neutron diffraction
- Petersburg Nuclear Physics Institute, Gatchina, 188300 St-Petersburg (Russian Federation)
- Institut fuer Physik der Kondensierten Materie, Technische Universitaet Braunschweig, D-38106 Braunschweig (Germany)
- GKSS Forschungszentrum, 21502 Geesthacht (Germany)
The magnetic structure of Fe{sub 1-x}Co{sub x}Si single crystals with x=0.10,0.15,0.20,0.50 has been studied by small angle polarized neutron diffraction and superconducting quantum interference device measurements. Experiments have shown that in zero field the compounds with x=0.1,0.15 have a well-defined tendency to order in the one-handed spiral along <100> axes due to the anisotropic exchange, that, however, decreases with increasing Co concentration x. The magnetic structure of Fe{sub 1-x}Co{sub x}Si with x=0.2,0.5 consists of spiral domains with randomly oriented spiral wave vector k. The applied magnetic field produces a single domain helix oriented along the field. The process of the reorientation starts at the field H{sub C1}. Further increase of the field leads to a magnetic phase transition from a conical to a ferromagnetic state near H{sub C2}. In the critical range near T{sub C} the integral intensity of the Bragg reflection shows a well-pronounced minimum at H{sub fl} attributed to a k flop of the helix wave vector. On the basis of our experiments we built the H-T phase diagram for each compound. It is shown that the same set of the parameters governs the magnetic properties of these compounds k, H{sub C1}, H{sub fl}, and H{sub C2}. Our experimental findings are well interpreted in the framework of a recently developed theory [Phys. Rev. B 73, 174402 (2006)] for cubic magnets with Dzyaloshinskii-Moriya (DM) interaction. In particular, the theory suggests an additional quantum term in the magnetic susceptibility caused by the DM interaction which is in good agreement with the experiment.
- OSTI ID:
- 21052816
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 76, Issue 22; Other Information: DOI: 10.1103/PhysRevB.76.224424; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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