R. Mattana and J. , Figure 4.1: Summary of observation on Ga-GeMn and As-GeMn samples. Main conclusions are as follows: 5

S. A. Wolf, A. Y. Chtchelkanova, and D. M. Treger, Spintronics???A retrospective and perspective, IBM Journal of Research and Development, vol.50, issue.1, p.101, 2006.
DOI : 10.1147/rd.501.0101

N. F. Mott, The Electrical Conductivity of Transition Metals, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.153, issue.880, p.699, 1936.
DOI : 10.1098/rspa.1936.0031

P. M. Tedrow and R. Meservey, Spin-Dependent Tunneling into Ferromagnetic Nickel, Physical Review Letters, vol.26, issue.4, p.192, 1971.
DOI : 10.1103/PhysRevLett.26.192

M. Johnson and R. H. Silsbee, Interfacial charge-spin coupling: Injection and detection of spin magnetization in metals, Physical Review Letters, vol.55, issue.17, p.1790, 1985.
DOI : 10.1103/PhysRevLett.55.1790

M. N. Baibich, J. M. Broto, A. Fert, F. Nguyen-van-dau, F. Petroff et al., Giant Magnetoresistance of (001)Fe/(001)Cr Magnetic Superlattices, Physical Review Letters, vol.61, issue.21, p.2472, 1988.
DOI : 10.1103/PhysRevLett.61.2472

G. Banisch, P. Grunberg, F. Saurenbach, and W. Zinn, Enhanced magnetoresistance in layered magnetic structures with antiferromagnetic interlayer exchange, Physical Review B, vol.39, issue.7, p.4828, 1989.
DOI : 10.1103/PhysRevB.39.4828

S. Datta and B. Das, Electronic analog of the electro???optic modulator, Applied Physics Letters, vol.56, issue.7, p.665, 1990.
DOI : 10.1063/1.102730

G. Schmidt, D. Ferrand, L. W. Molenkamp, A. T. Filip, and B. , Fundamental obstacle for electrical spin injection from a ferromagnetic metal into a diffusive semiconductor, Physical Review B, vol.62, issue.8, p.4790, 2000.
DOI : 10.1103/PhysRevB.62.R4790

H. Ohno, Making Nonmagnetic Semiconductors Ferromagnetic, Science, vol.281, issue.5379, p.951, 1998.
DOI : 10.1126/science.281.5379.951

J. K. Furdyna, Diluted magnetic semiconductors, Journal of Applied Physics, vol.64, issue.4, p.29, 1988.
DOI : 10.1063/1.341700

]. F. Matsukura, H. Ohno, A. Shen, and Y. Sugawara, Transport properties and origin of ferromagnetism in (Ga,Mn)As, Physical Review B, vol.57, issue.4, p.2037, 1998.
DOI : 10.1103/PhysRevB.57.R2037

T. Dietl, H. Ohno, F. Matsukura, J. Cibert, and D. Ferrand, Zener Model Description of Ferromagnetism in Zinc-Blende Magnetic Semiconductors, Science, vol.287, issue.5455, p.1019, 2000.
DOI : 10.1126/science.287.5455.1019

A. P. Li, C. Zeng, K. Van-benthem, M. F. Chisholm, J. Shen et al., Dopant segregation and giant magnetoresistance in manganese-doped germanium, Physical Review B, vol.75, issue.20, p.201201, 2007.
DOI : 10.1103/PhysRevB.75.201201

D. Bougeard, S. Ahlers, A. Trampert, N. Sircar, and G. Abstreiter, Clustering in a Precipitate-Free GeMn Magnetic Semiconductor, Physical Review Letters, vol.97, issue.23, p.237202, 2006.
DOI : 10.1103/PhysRevLett.97.237202

M. Jamet, A. Barski, T. Devillers, V. Poydenot, R. Dujardin et al., High-Curie-temperature ferromagnetism in self-organized Ge1???xMnx nanocolumns, Nature Materials, vol.11, issue.8, p.653, 2006.
DOI : 10.1038/nmat1686

A. Bonanni, A. Navarro-quezada, T. Li, M. Wegscheider, Z. Matej et al., Controlled Aggregation of Magnetic Ions in a Semiconductor: An Experimental Demonstration, Physical Review Letters, vol.101, issue.13, p.135502, 2006.
DOI : 10.1103/PhysRevLett.101.135502

S. Kuroda, N. Nishizawa, K. Takita, M. Mitome, Y. Bando et al., Origin and control of high-temperature ferromagnetism in semiconductors, Nature Materials, vol.63, issue.6, p.440, 2007.
DOI : 10.1038/nmat1910

K. Sato, H. Katayama-yoshida, and P. H. Dederichs, High Curie Temperature and Nano-Scale Spinodal Decomposition Phase in Dilute Magnetic Semiconductors, Japanese Journal of Applied Physics, vol.44, issue.No. 30, p.948, 2005.
DOI : 10.1143/JJAP.44.L948

T. Fukushima, K. Sato, H. Katayama-yoshida, and P. H. Dederichs, Spinodal Decomposition under Layer by Layer Growth Condition and High Curie Temperature Quasi-One-Dimensional Nano-Structure in Dilute Magnetic Semiconductors, Japanese Journal of Applied Physics, vol.45, issue.No. 15, p.416, 2006.
DOI : 10.1143/JJAP.45.L416

I. Zutic, J. Fabian, and S. C. Erwin, Spin Injection and Detection in Silicon, Physical Review Letters, vol.97, issue.2, p.26602, 2006.
DOI : 10.1103/PhysRevLett.97.026602

Y. D. Park, A. T. Hanbicki, S. C. Erwin, C. S. Hellberg, J. M. Sullivan et al., A Group-IV Ferromagnetic Semiconductor: MnxGe1-x, Science, vol.295, issue.5555, p.651, 2002.
DOI : 10.1126/science.1066348

T. B. Massalski, Binary Alloy Phase Diagram, 1990.

R. B. Morgunov, A. J. Dmitriev, and O. L. Kazakova, Percolation ferromagnetism and spin waves in Ge:Mn thin films, Physical Review B, vol.80, issue.8, p.85205, 2009.
DOI : 10.1103/PhysRevB.80.085205

Y. J. Cho, C. H. Kim, H. S. Kim, W. S. Lee, S. Park et al., (M = Mn, Fe, and Co) Nanowires, Chemistry of Materials, vol.20, issue.14, p.4694, 2008.
DOI : 10.1021/cm7035635

P. D. Padova, J. Ayoub, I. Berbezier, P. Perfetti, C. Quaresima et al., nanoscopic clusters on the electronic and magnetic properties, Physical Review B, vol.77, issue.4, p.45203, 2008.
DOI : 10.1103/PhysRevB.77.045203

L. Morresi, J. Ayoub, N. Pinto, M. Ficcadenti, R. Murri et al., Formation of Mn5Ge3 nanoclusters in highly diluted MnxGe1???x alloys, Materials Science in Semiconductor Processing, vol.9, issue.4-5, p.836, 2006.
DOI : 10.1016/j.mssp.2006.08.056

C. Bihler, C. Jaeger, T. Vallaitis, M. Gjukic, M. S. Brandt et al., Structural and magnetic properties of Mn5Ge3 clusters in a dilute magnetic germanium matrix, Applied Physics Letters, vol.88, issue.11, p.112506, 2006.
DOI : 10.1063/1.2185448

Y. D. Park, A. Wilson, A. T. Hanbicki, J. E. Mattson, T. Ambrose et al., Magnetoresistance of Mn:Ge ferromagnetic nanoclusters in a diluted magnetic semiconductor matrix, Applied Physics Letters, vol.78, issue.18, p.2739, 2001.
DOI : 10.1063/1.1369151

L. Ottaviano, M. Passacantando, A. Verna, R. Gunnella, E. Principi et al., Direct structural evidences of Mn dilution in Ge, Journal of Applied Physics, vol.100, issue.6, p.63528, 2006.
DOI : 10.1063/1.2337388

J. Kang, G. Kim, S. C. Wi, S. S. Lee, S. Choi et al., Spatial Chemical Inhomogeneity and Local Electronic Structure of Mn-Doped Ge Ferromagnetic Semiconductors, Physical Review Letters, vol.94, issue.14, p.147202, 2005.
DOI : 10.1103/PhysRevLett.94.147202

S. Ahlers, D. Bougeard, N. Sircar, G. Abstreiter, A. Trampert et al., films: Precipitation of intermetallic nanomagnets, Physical Review B, vol.74, issue.21, p.214411, 2006.
DOI : 10.1103/PhysRevB.74.214411

F. Matsukura, H. Ohno, A. Shen, and Y. Sugawara, Transport properties and origin of ferromagnetism in (Ga,Mn)As, Physical Review B, vol.57, issue.4, p.2037, 1998.
DOI : 10.1103/PhysRevB.57.R2037

F. Tsui, L. He, L. Ma, A. Tkachuk, Y. S. Chu et al., Novel Germanium-Based Magnetic Semiconductors, Physical Review Letters, vol.91, issue.17, p.177203, 2003.
DOI : 10.1103/PhysRevLett.91.177203

J. X. Deng, Y. F. Tain, S. M. He, H. L. Bai, T. S. Xu et al., Strong anisotropy of magnetization and sign reversion of ordinary Hall coefficient in single crystal Ge1???xMnx magnetic semiconductor films, Applied Physics Letters, vol.95, issue.6, p.62513, 2009.
DOI : 10.1063/1.3206664

O. Riss, A. Gerber, I. Ya, A. Korenblit, M. Suslov et al., Magnetization-driven metal-insulator transition in strongly disordered Ge:Mn magnetic semiconductors, Physical Review B, vol.79, issue.24, p.241202, 2009.
DOI : 10.1103/PhysRevB.79.241202

A. Y. Cho and J. R. Arthur, Molecular beam epitaxy, Progress in Solid State Chemistry, vol.10, p.157, 1975.
DOI : 10.1016/0079-6786(75)90005-9

URL : https://hal.archives-ouvertes.fr/hal-01492483

T. Devillers, Etude des propriétés physiques des phases de Ge 1?x Mn x ferromagnetiques pour l'´ electronique de spin, 2008.

A. Ichimiya and P. , Cohen Reflection High Energy Electron Diffraction, 2004.

J. E. Hilliard, Spinodal Decomposition in Phase Transformation, 1970.

E. H. Hall, On a New Action of the Magnet on Electric Currents, American Journal of Mathematics, vol.2, issue.3, p.287, 1879.
DOI : 10.2307/2369245

N. A. Sinitsyn, Semiclassical theories of the anomalous Hall effect, Journal of Physics: Condensed Matter, vol.20, issue.2, p.23201, 2008.
DOI : 10.1088/0953-8984/20/02/023201

L. Berger, Side-Jump Mechanism for the Hall Effect of Ferromagnets, Physical Review B, vol.2, issue.11, p.4559, 1970.
DOI : 10.1103/PhysRevB.2.4559

P. L. Rossiter, The Electrical Resistivity of Metals and Alloys, 2009.

J. Q. Xiao, J. S. Jiang, and C. L. Chien, Giant magnetoresistance in nonmultilayer magnetic systems, Physical Review Letters, vol.68, issue.25, p.3749, 1992.
DOI : 10.1103/PhysRevLett.68.3749

A. E. Berkowitz, J. R. Mitchell, M. J. Carey, A. P. Young, S. Zhang et al., Giant magnetoresistance in heterogeneous Cu-Co alloys, Physical Review Letters, vol.68, issue.25, p.3745, 1992.
DOI : 10.1103/PhysRevLett.68.3745

A. Lecycuras, Arsenic segregation and passivation in the heteroepitaxy of Ge/GaAs, Applied Physics Letters, vol.66, issue.14, p.1800, 1995.
DOI : 10.1063/1.113326

G. Ottaviani, C. Canali, C. Jacoboni, A. A. Quaranta, and K. Zanio, Hole mobility and Poole???Frenkel effect in CdTe, Journal of Applied Physics, vol.44, issue.1, p.360, 1973.
DOI : 10.1063/1.1661888

W. Zhu, Z. Zhang, and E. Kaxiras, Dopant-Assisted Concentration Enhancement of Substitutional Mn in Si and Ge, Physical Review Letters, vol.100, issue.2, p.27205, 2008.
DOI : 10.1103/PhysRevLett.100.027205

A. Fert and H. Jaffres, Conditions for efficient spin injection from a ferromagnetic metal into a semiconductor, Physical Review B, vol.64, issue.18, p.184420, 2001.
DOI : 10.1103/PhysRevB.64.184420

M. J. Uren, Magnetic delocalisation of a two-dimensional electron gas and the quantum law of electron-electron scattering, Journal of Physics C: Solid State Physics, vol.14, issue.13, p.395, 1981.
DOI : 10.1088/0022-3719/14/13/003

T. C. Schulthess and W. H. Butler, Electronic structure and magnetic interactions in Mn doped semiconductors, Journal of Applied Physics, vol.89, issue.11, p.7021, 2001.
DOI : 10.1063/1.1359456

H. H. Woodbury and W. W. Tyler, Properties of Germanium Doped with Manganese, Physical Review, vol.100, issue.2, p.659, 1955.
DOI : 10.1103/PhysRev.100.659

R. Newman, H. H. Woodbury, and W. W. Tyler, Photoconductivity in Manganese-Doped Germanium, Physical Review, vol.102, issue.3, p.613, 1956.
DOI : 10.1103/PhysRev.102.613

. Dans-leséchantillonsleséchantillons-ga-gemn, cellesci sont paralléles entre elles, ou enchevêtrées, suivant la morphologie de surface initiale Les mesures de magnétométrie révélent deux phases magnétiques : les nanocolonnes ferromagnétiques avec une température de Curie de 150 K, et la matrice de germanium, rendue paramagnétique par la présence de Mn dilué. Les mesures de magnétotransport montrent que ces couches sont de type p, et révélent un l'effet Hall anormal (AHE) et plusieurs contributionsácontributionsá la magnétorésistance : une magnétorésistance géante négative, ´ a basse température, la magnétorésistante orbitale, parabolique, et une contribution supplémentairé a faible champ. Un calcul des propriétés de magnétotransport a ´ eté commencé en s'appuyant sur des hypothéses de la structure de bande entre les inclusions riches en Mn et la matrice semiconductrice de type p : celui-ci montre que la présence d

. Dans-leséchantillonsleséchantillons-as-gemn, avec une décomposition spinodale qui perd son caractére bidimensionnel pour devenir tridimensionnelle, avec la formation d'agrégats riches en Mn (température de Curie de l'ordre de 50 K) et d'agrégats de la phase ferromagnétique connue Ge 3 M n 5 . La compensation entre Mn (accepteur) et As (donneur) gouverne les propriétés de transport. Dans les couches de type n, une forte anisotropie de la magnétorésistance est observée, dont nous montrons qu'elle est dué a des effets de localisation faible. Une autre contributionácontribution´contributioná la magnétorésistance est observée, que nous suggérons d'attribueráattribuerá une magnétorésistance tunneí a travers la jonction Schottky qui se formé a l'interface entre les inclusions riches en Mn, qui sont métalliques