Europhys. Lett.
Volume 65, Number 4, February 2004
Page(s) 553 - 559
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 February 2004
Europhys. Lett., 65 (4) , pp. 553-559 (2004)
DOI: 10.1209/epl/i2003-10120-5

Ferromagnetic $\chem{Ga}$ 1-x $\chem{Mn}$ x $\chem{N}$ epilayers vs. antiferromagnetic $\chem{GaMn_{3}N}$ clusters

R. Giraud1, S. Kuroda1, S. Marcet1, E. Bellet-Amalric1, X. Biquard1, B. Barbara2, D. Fruchart3, D. Ferrand1, J. Cibert1 and H. Mariette1

1  CEA-CNRS group "Nanophysique et Semi-conducteurs" Laboratoire de Spectrométrie Physique, Université Joseph Fourier-Grenoble I, and DRFMC-SP2M, CEA Grenoble - 38054 Grenoble, France
2  Laboratoire de Magnétisme Louis Néel, CNRS - BP166, 38042 Grenoble, France
3  Laboratoire de Cristallographie, CNRS - 38042 Grenoble Cedex-09, France

(Received 14 July 2003; accepted in final form 8 December 2003)

$\chem{Mn}$-doped wurtzite $\chem{GaN}$ epilayers have been grown by nitrogen plasma-assisted molecular-beam epitaxy. Correlated SIMS, structural and magnetic measurements show that the incorporation of $\chem{Mn}$ strongly depends on the conditions of the growth. Hysteresis loops which persist at high temperature do not appear to be correlated to the presence of $\chem{Mn}$. Samples with up to 2% $\chem{Mn}$ are purely substitutional $\chem{Ga}$ 1-x $\chem{Mn}$ x $\chem{N}$ epilayers, and exhibit paramagnetic properties. At higher $\chem{Mn}$ contents, precipitates are formed which are identified as $\chem{GaMn_{3}N}$ clusters by X-ray diffraction and absorption: this induces a decrease of the paramagnetic magnetisation. Samples co-doped with enough $\chem{Mg}$ exhibit a new feature: a ferromagnetic component is observed up to $T_{\ab{c}}\sim 175$ $\un{K}$, which cannot be related to superparamagnetism of unresolved magnetic precipitates.

75.50.Pp - Magnetic semiconductors.
71.55.Eq - III-V semiconductors.
61.10.Ht - X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc..

© EDP Sciences 2004