Study of ferromagnetism in Mn doped ZnO dilute semiconductor system

The wide band gap semiconductor ZnO when doped with a very low percent of some transition metal ions can exhibit above room temperature ferromagnetism, transforming it into a unique compound for spin-electronic applications. In the present work we have compared the electronic structure of two polycr...

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Bibliographic Details
Published inJournal of physics. Conference series Vol. 153; no. 1; p. 012065
Main Authors Singhal, R K, Dhawan, M S, Gaur, S K, Dolia, S N, Kumar, Sudhish, Shripathi, T, Deshpande, U P, Xing, Y T, Saitovitch, Elisa, Garg, K B
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 01.03.2009
Subjects
Diamagnetism
Dilution
Electron spin
Electronic structure
Ferromagnetism
Low temperature
Magnetic properties
Magnetic semiconductors
Magnetism
Oxidation
Oxygen content
Pellets
Photoelectric emission
Physics
Room temperature
Semiconductor materials
Transition metals
Wurtzite
X ray absorption
Zinc oxide
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Summary:The wide band gap semiconductor ZnO when doped with a very low percent of some transition metal ions can exhibit above room temperature ferromagnetism, transforming it into a unique compound for spin-electronic applications. In the present work we have compared the electronic structure of two polycrystalline Zn1-xMnxO pellets (for x=0.02 and 0.04), prepared by low temperature processing, and carefully characterized. The Rietveld refinement of the XRD patters established that the samples have the ZnO lattice with ZnS type Wurtzite hexagonal symmetry and no detectable impurities. The samples exhibit distinctly different magnetic properties. The pure ZnO pellet shows a diamagnetic behaviour, the 2% sample displayed a clear FM ordering at 300 K while the 4% sample did not show any ordering even upon cooling. Their electronic structure has been investigated using x-ray absorption and x-ray photoemission spectroscopy with an aim to find out how the changes in the electronic structure can correlate to the magnetic properties in such diluted magnetic semiconductor materials. The results show that most of the Mn ions of the ferromagnetic sample are in the divalent state. For the higher Mn percent nonmagnetic sample, a larger contribution of higher oxidation Mn states are dominant and the oxygen content also increases. The two factors can be correlated to the suppressed ferromagnetism, though it is hard to exactly predict that which of these two factors weighs more.
ISSN:1742-6596
1742-6588
1742-6596
DOI:10.1088/1742-6596/153/1/012065