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Preparation and characterization of hexagonal MnTe and ZnO layers

Ewa Przezdziecka 4Eliana Kaminska 1Elzbieta Dynowska 2Elżbieta Janik 2Renata Butkute 2Witold Daniel Dobrowolski 2Maciej Sawicki 4Henryk Kepa 3Rafał Jakieła 2,5Marta Aleszkiewicz 2Jacek Kossut 4

1. Institute of Electron Technology (ITE), al. Lotników 32/46, Warszawa 02-668, Poland
2. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
3. Warsaw University, Institute of Experimental Physics (IEP UW), Hoża 69, Warszawa 00-681, Poland
4. Polish Academy of Sciences, Institute of Physics and ERATO Semiconductor Spintronics Project, al. Lotników 32/46, Warszawa 02-668, Poland
5. Institute of Electronic Materials Technology (ITME), Wólczyńska 133, Warszawa 01-919, Poland


In the first part of this work we present the results of the investigation of high crystalline quality MnTe layers grown epitaxially by MBE. It is known that the bulk MnTe with hexagonal crystalline structure of NiAs is a magnetic semiconductor with a high Neel temperature (310K) [1]. Thin layers of MnTe exhibit also antiferromagnetic properties, and for this reason, they can be used as the pinning layer in semiconductor spin valves. Characterization of our samples by X-ray diffraction revealed a high crystalline quality of hexagonal structure of NiAs-type.With lattice parameters of the unit cell are a=4.166A and c=6.694A. The optical transmission spectra of MnTe measured at low temperature gave a possibility to evaluate the energy gap (1.7 eV). In order to establish the Neel temperature the neutron diffraction measurements were performed. The temperature of the antiferromagnetic transition for our samples was 284.1K
The second part of this work is dedicated to ZnO:N:Mn. Theoretical works predicted that this material can be a ferromagnetic above the room temperature [2].The metallic Zn and ZnTe were grown by MBE. In order p-type conductivity in ZnTe is achieved by nitrogen doping. So, a part of our samples was doped with nitrogen, and some contained few percents of Mn. SIMS measurements help us to evaluate the quantity of N atoms in the ZnTe:N and Zn:N. After growth all samples were oxidized by keeping them in O2 flow at 600-650oC.The spectra of X-ray diffraction measurements demonstrated only the peaks related to ZnO crystal and substrates. Detailed SQUID measurements of Mn-doped ZnO detected a very weak magnetization persisting up to high temperatures.
[1]N.Kunitomi, Y.Hamaguchi, S.Amzai, Phys.,Vol. 25,p. 568(1964).
[2]T.Dietl, H.Ohno, F.Matsukura, J.Cibert and D.Ferrand,Science,Vol.287, p. 1019(2000).


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Presentation: poster at E-MRS Fall Meeting 2004, Symposium F, by Ewa Przezdziecka
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-05-19 10:42
Revised:   2009-06-08 12:55