High-Curie-temperature ferromagnetism in self-organized Ge1-xMnx nanocolumns.
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.
Jamet
Matthieu
M
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
Barski
André
A
Devillers
Thibaut
T
Poydenot
Valier
V
Dujardin
Romain
R
Bayle-Guillemaud
Pascale
P
Rothman
Johan
J
Bellet-Amalric
Edith
E
Marty
Alain
A
Cibert
Joël
J
Mattana
Richard
R
Tatarenko
Serge
S