On the formation of magnetic nanocomposites and impurity complexes in GaN doped with Fe and Mn
|Andrea Navarro-Quezada 1, Giulia Capuzzo 1, Sylwia I. Stefanowicz 2, Thibaut Devillers 1, Wiktor Stefanowicz 2, Tian Li 1, Bogdan Faina 1, Maciej Sawicki 2, Tomasz Dietl 2,3,4,5, Alberta Bonanni 1|
1. Institut für Halbleiter und Feskörperphysik, Johannes Kepler Universität (FKP-JKU), Altenbergerstr. 69, Linz 4040, Austria
The control over the aggregation of magnetic ions in a non-magnetic semiconductor matrix constitutes a new way to realize semiconductor/ferromagnetic nanocomposites with hitherto unexplored but striking functionalities.
With this work we show – in the case of the model systems (Ga,Fe)N and Ga,Mn)N fabricated by metalorganic vapor phase epitaxy – that there is a critical and systematic dependence of the crystalline structure, magnetic ions incorporation and macroscopic properties of these composite material systems on the fabrication conditions and on the co-doping with shallow impurities.
For phase-separated (Ga,Fe)N, we show that the controlled formation of various Fe-rich embedded nanocrystals with peculiar stoichiometry and magnetic properties is responsible for the observed contributions to the overall magnetization of the layers, namely: i) paramagnetic – due to dilute Fe3+; ii) ferromagnetic; and iii) a component linear in the magnetic field, associated with antiferromagnetic interactions – originating from FexN (x ≤ 2) . Furthermore, the effect of Mg co-doping and deposition mode on the Fe distribution is discussed, together with the ways to obtain a controlled and well-defined arrangement of monophase Fe-rich nanocrystals embedded in the GaN host .
In the case of (Ga,Mn)N, we demonstrate that co-doping with Mg over a certain threshold of doping allows to modify the charge- and spin-state of Mn via the formation of impurity complexes Mn-kMg, where k depends on the fabrication conditions. The significance of these results is discussed in view of the prospects of embedded magnetic nanocrystals and impurity complexes for photonics and solotronics applications .
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 A. Navarro-Quezada et al. Appl. Phys. Lett. 101, 081911 (2012)
 P. Koenraad and M. Flatté, Nat. Mat. 10, 91-100 (2011)
Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 2, by Alberta Bonanni
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17
Submitted: 2013-05-09 16:11 Revised: 2013-05-09 16:12