Magnetotransport studies of Ga(Mn,Fe)N bulk crystals

C. Jastrzebski 2Wojtek Gebicki 2Michal Bockowski 1B. Strojek 3T. Szyszko 3Sławomir Podsiadło 3

1. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland
2. Warsaw University of Technology, Faculty of Physics, Koszykowa 75, Warszawa 00-662, Poland
3. Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, Warszawa 00-664, Poland

Abstract

GaN based DMS are considered the very promising wide band gap materials for spintronic applications. Electric properties (carrier concentration, mobility) of the materials are crucial for understanding the nature of magnetism in these materials and in consequence for use in possible applications. It seems undoubtedly that electric and magnetic properties of the materials are tightly coupled.
In our work we studied two types of samples GaMnN and GaFeN. The Mn doped samples were grown by high pressure method and chemical transport method and GaFeN samples were grown only by chemical transport method. Some of the GaN:Fe samples were co doped with Si atoms.
Van der Pauw resistance measurements and Hall resistance measurements were applied for the first samples and five contacts bar type method for the second ones. Measurements were performed in the range of temperature from 4.2 to 250K and at magnetic field up to 7 T. We obtained positive magnetoresistance for GaMnN but some GaFeN samples (especially the ones doped with Si atoms) indicates negative magnetoresistance.
Carrier concentration was extracted from the linear slope of the Hall resistance versus magnetic field. Electrons concentration of about 10e19 cm-3 was determined for GaMnN samples and it didn't depend from growth method but for GaFeN samples concentration exceeded 10e21 cm-3 indicating metallic type of the samples. At low temperature deviation from linearity of Hall resistance versus magnetic field was observed for small values of B and will be further discussed.
Magnetic properties of the same GaFeN samples were studied elsewhere and the magnetic measurements show coexistence of para- and ferromagnetic phases in the same sample. The effect was also visible in GaMnN samples but the ferromagnetic phase was significant weaker in this case.
Temperature dependence of resistance and Hall resistance of the samples was measured and will be discussed.
Partially supported by KBN grant PBZ-KBN-044/P03/2001.

 

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Presentation: oral at E-MRS Fall Meeting 2003, Symposium A, by Cezariusz Jastrzebski
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-27 23:06
Revised:   2009-06-08 12:55