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High-Curie-temperature ferromagnetism in self-organized Ge1−xMnx nanocolumns

Nature Materials volume 5, pages 653–659 (2006)Cite this article

Abstract

The emerging field of spintronics would be dramatically boosted if room-temperature ferromagnetism could be added to semiconductor nanostructures that are compatible with silicon technology. Here, we report a high-TC (>400K) ferromagnetic phase of (Ge,Mn) epitaxial layer. The manganese content is 6%, and careful structural and chemical analyses show that the Mn distribution is strongly inhomogeneous: we observe eutectoid growth of well-defined Mn-rich nanocolumns surrounded by a Mn-poor matrix. The average diameter of these nanocolumns is 3nm and their spacing is 10nm. Their composition is close to Ge2Mn, which corresponds to an unknown germanium-rich phase, and they have a uniaxially elongated diamond structure. Their Curie temperature is higher than 400K. Magnetotransport reveals a pronounced anomalous Hall effect up to room temperature. A giant positive magnetoresistance is measured from 7,000% at 30K to 200% at 300K and 9T, with no evidence of saturation.

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Figure 1: Transmission electron micrographs of an 80-nm-thick Ge0.94Mn0.06 film.
Figure 2: Mn chemical maps and Mn profiles derived from electron energy-loss spectroscopy.
Figure 3: Magnetic measurements using a SQUID magnetometer.
Figure 4: In-plane magnetotransport measured on 200-μm-wide Hall bars from a Ge0.94Mn0.06 film.

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Author notes

  1. Richard Mattana

    Present address: Unité Mixte de Physique CNRS-Thalès, 91767, Palaiseau Cedex

  2. Richard Mattana

    Present address: Université Paris-Sud, 91405, Orsay, France

Authors and Affiliations

  1. Département de Recherche Fondamentale sur la Matière Condensée, Service de Physique des Matériaux et Microstructures, CEA Grenoble, 17 avenue des Martyrs, 38054, Grenoble, Cedex 9, France

    Matthieu Jamet, André Barski, Thibaut Devillers, Valier Poydenot, Romain Dujardin, Pascale Bayle-Guillemaud, Edith Bellet-Amalric, Alain Marty & Richard Mattana

  2. Laboratoire d'Electronique de Technologie de l'Information, Laboratoire Infrarouge, CEA Grenoble, 17 avenue des Martyrs, 38054, Grenoble, Cedex 9, France

    Johan Rothman

  3. Laboratoire Louis Néel, CNRS, BP166, 38042, Grenoble, Cedex 9, France

    Joël Cibert

  4. Laboratoire de Spectrométrie Physique, BP 87, 38402, Saint-Martin d'Hères, France

    Serge Tatarenko

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  1. Matthieu Jamet
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Correspondence to Matthieu Jamet.

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Jamet, M., Barski, A., Devillers, T. et al. High-Curie-temperature ferromagnetism in self-organized Ge1−xMnx nanocolumns. Nature Mater 5, 653–659 (2006). https://doi.org/10.1038/nmat1686

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