High-Curie-temperature ferromagnetism in self-organized GeMn nanocolumns

Matthieu Jamet (1) , André Barski (1) , Thibaut Devillers (1) , Valier Poydenot (1) , Romain Dujardin (1) , Pascale Bayle-Guillemaud (1) , Johan Rothman (2) , Edith Bellet-Amalric (1) , Alain Marty (1) , Joel Cibert (3) , Richard Mattana (1) , Serge Tatarenko (4)

1 SP2M - UMR 9002 - Service de Physique des Matériaux et Microstructures
2 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
3 LLN - Laboratoire Louis Néel
4 LSP - Laboratoire de Spectrométrie Physique

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 (>400 K) 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 3 nm 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 400 K. 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 9 T, with no evidence of saturation.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Matthieu Jamet, André Barski, Thibaut Devillers, Valier Poydenot, Romain Dujardin, et al.. High-Curie-temperature ferromagnetism in self-organized GeMn nanocolumns. Nature Materials, 2006, 5, pp.653. ⟨hal-00108465⟩