Article abstract
Nature Materials 5, 653 - 659 (2006)
doi:10.1038/nmat1686
Subject Categories: Semiconductors | Nanoscale materials | Magnetic materials
High-Curie-temperature ferromagnetism in self-organized Ge1-xMnx nanocolumns
Matthieu Jamet1, André Barski1, Thibaut Devillers1, Valier Poydenot1, Romain Dujardin1, Pascale Bayle-Guillemaud1, Johan Rothman2, Edith Bellet-Amalric1, Alain Marty1, Joël Cibert3, Richard Mattana1,5 and Serge Tatarenko4
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.
- 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
- Laboratoire d'Electronique de Technologie de l'Information, Laboratoire Infrarouge, CEA Grenoble, 17 avenue des Martyrs, 38054 Grenoble Cedex 9, France
- Laboratoire Louis Néel, CNRS, BP166, 38042 Grenoble Cedex 9, France
- Laboratoire de Spectrométrie Physique, BP 87, 38402 Saint-Martin d'Hères, France
- Present address: Unité Mixte de Physique CNRS-Thalès, 91767 Palaiseau Cedex and Université Paris-Sud, 91405 Orsay, France
Correspondence to: Matthieu Jamet1 e-mail: matthieu.jamet@cea.fr
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