Publications (4)6.01 Total impact
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Article: Pure paramagnetic behavior in Mn-doped ZnO semiconductors
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ABSTRACT: Polycrystaline Mn-doped zinc oxides ( Zn <sub>1-x</sub> Mn <sub>x</sub> O ) were synthesized by coprecipitation method with x varying between 0.01 and 0.1. Raman spectroscopy indicates the appearance of an additional mode which is an indicator for the incorporation of Mn ions into the ZnO host matrix. The magnetic properties have been studied by electron paramagnetic resonance (EPR) spectroscopy. The Mn-related EPR spectra exhibit the expected pattern for isolated Mn ions. Temperature dependence of the reciprocal integrated EPR signal follows a Curie law indicating a typical paramagnetic behavior for x≤0.05 .Journal of Applied Physics 05/2006; · 2.17 Impact Factor -
Article: Antiferromagnetism in bulk Zn1−xCoxO magnetic semiconductors prepared by the coprecipitation technique
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ABSTRACT: Polycrystalline Zn1−xCoxO diluted magnetic semiconductors have been prepared by coprecipitation technique in the concentration range 0 ⩽ x ⩽ 0.1. Structure, composition analysis, and optical absorption measurements revealed that cobalt is incorporated into the lattice, as Co2+ substituting Zn2+ ions, forming a solid solution with wurtzite structure instead of Co precipitates. Room- and low-temperature magnetization measurements reveal a paramagnetic behavior for the Co-doped ZnO samples with a paramagnetic Co amount smaller than the nominal concentration. χT versus T evidenced that the remaining Co is antiferromagnetically coupled through oxygen. This is further supported by a simple model that shows that as the Co concentration increases the amount of nearest neighbors Co atoms increases thus giving antiferromagnetic coupling and reducing the paramagnetic contribution.Applied Physics Letters 07/2005; 87(5):052501-052501-3. · 3.84 Impact Factor -
Article: No ferromagnetism in Mn doped ZnO semiconductors
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ABSTRACT: Polycrystalline Zn1 − xMnxO was synthesized by co-precipitation method with xvarying between 0.01 and 0.10. Although X-ray diffraction patterns show a typical würtzite structure with no additional peaks for all samples, Raman spectroscopy indicates the appearance of an additional mode in correlation with the absorption edge shift observed by UV–Vis spectroscopy and which is an indicator for incorporation of Mn ions into the ZnO matrix. The magnetic properties have been studied by both EPR spectroscopy and SQUID magnetometry. Their temperature dependence follows a Curie law indicating a typical paramagnetic behavior for x ⩽ 0.05 and no indication of ferromagnetism nor antiferromagnetism.Chemical Physics Letters. -
Article: Bulk Zn1 − xCoxO magnetic semiconductors prepared by hydrothermal technique
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ABSTRACT: We have used a hydrothermal technique to synthesize polycrystalline Zn1 − xCoxO diluted magnetic semiconductor. The synthesis temperature was of 240 °C and the Co concentration of 10 at.%. X-ray diffraction indicates that the Co-doped ZnO thus prepared has the pure ZnO wurtzite structure without any significant change in the cell parameters. Optical absorption measurements show several absorption bands that are due to the transitions between the crystal-field-split 3d levels of tetrahedral Co2+ substituting Zn2+ ions. Room temperature magnetization measurements reveal a paramagnetic behavior for the Co-doped ZnO samples. This is attributed to the absence of free carriers.Chemical Physics Letters.
