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Ferromagnetism in lightly Gd doped GaN: The role of defects

Published online by Cambridge University Press:  02 March 2011

J. K. Mishra ,
S. Dhar ,
M. A. Khaderabad  and
O. Brandt
J. K. Mishra
Affiliation:
Physics Department, Indian Institute of Technology Bombay, Powai Mumbai - 400076, India.
S. Dhar
Affiliation:
Physics Department, Indian Institute of Technology Bombay, Powai Mumbai - 400076, India.
M. A. Khaderabad
Affiliation:
Electrical Engineering Department, Indian Institute of Technology Bombay, Powai Mumbai-400076, India
O. Brandt
Affiliation:
Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin, Germany.
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Abstract

Gd:GaN layers grown with different Gd concentrations by molecular beam epitaxy (MBE) are studied using photoconductivity and photo-thermoelectric power spectroscopy. Our study reveals that the incorporation of Gd produces a large concentration of acceptor-like defects in the GaN lattice. The defect band is found to be located ~450meV above the valence band. Moreover, the concentration of defects is found to increase with the Gd concentration. The effect of annealing on the structural and the magnetic properties of GaN implanted with Gd is also investigated. A clear correlation between the saturation magnetization and the defect density is observed in implanted samples. The colossal magnetic moment per Gd ion and the ferromagnetism observed in this material is explained in terms of the formation of giant defect cluster around each Gd ion.

Keywords

photoconductivitydefectsmagnetic
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1290: Symposium I – Magnetism and Correlated Electronic Structure of Nitrides—Rare-Earth and Transition Metals as Constituents and Dopants , 2011 , mrsf10-1290-i03-01
Copyright
Copyright © Materials Research Society 2011

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References

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