title: High-Curie-temperature ferromagnetism in self-organized Ge1-xMnx nanocolumns.
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 Ge(2)Mn, 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.
authors.affiliation: 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@cea.fr
authors.forename: Matthieu
authors.initials: M
authors.lastname: Jamet
authors.forename: André
authors.initials: A
authors.lastname: Barski
authors.forename: Thibaut
authors.initials: T
authors.lastname: Devillers
authors.forename: Valier
authors.initials: V
authors.lastname: Poydenot
authors.forename: Romain
authors.initials: R
authors.lastname: Dujardin
authors.forename: Pascale
authors.initials: P
authors.lastname: Bayle-Guillemaud
authors.forename: Johan
authors.initials: J
authors.lastname: Rothman
authors.forename: Edith
authors.initials: E
authors.lastname: Bellet-Amalric
authors.forename: Alain
authors.initials: A
authors.lastname: Marty
authors.forename: Joël
authors.initials: J
authors.lastname: Cibert
authors.forename: Richard
authors.initials: R
authors.lastname: Mattana
authors.forename: Serge
authors.initials: S
authors.lastname: Tatarenko