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Physical and structural properties of incomensurately modulated Fe 2 - x Ge intermetallic

Iron - germanium system has very rich phase diagram hosting variety of phases and compounds. One of them (FeGe) recently attracted much attention. In thin film form of this comp ound skyrmions were reported near room temperature (at 260K) [1]. Authors found that when thickness of crystal becomes greater than distance between skyrmions, more ordinary ferromagnetic phase starts to dominate. This discovery pushed further investigatio ns of iron - germanium system in context of spintronic applications. Here we report on investigation of Fe 2 - x Ge phase that has bulk ferromagnetic transition at 420 K. Transport properties show typical behavior of complex metallic alloys. Detailed structural analysis revealed that crystal structure can be described by incommensurately modulated distribution of vacancies in all six Fe sites of the Fe 2 Ge structure, while all Ge sites are fully occupied. Using the satellite reflections, the structure solution ha s been obtained in the superspace group P - 6m2(00γ)000. In the modulated structure, layer blocks of the FeGe and Fe 2 Ge composition aperiodically alternate along the hexagonal c - axis [1] X. Z. Yu, N. Kanazawa, Y. Onose, K. Kimoto, W. Z. Zhang, S. Ishiwata, Y. Matsui and Y. Tokura, Nature Materials 10 (2011) 106.

FeGe; phase diagram; ferromagnetic transition

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