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EPR study of the diluted magnetic semiconductor CuGa<inf>1-x</inf>Mn<inf>x</inf>Te<inf>2</inf>

Abstract:

Electron paramagnetic resonance (EPR) experiments were made in the diluted magnetic semiconductor CuGa1-xMnxTe2, in the temperature range 70<T<300 K. The samples were synthesized by direct fusion of stoichiometric mixtures of the elements, with Mn composition from x=0.0 to 0.25. The EPR spectra were measured as function of temperature, Mn composition, and field orientation. The temperature variation of the resonance field shows a critical point at about 235 K, and is associated with a transition from the ferromagnetic to the superparamagnetic state. The resonance field was also measured as a function of the field angle, and displays a well-defined uniaxial symmetry. This uniaxial field depends on the Mn concentration and is due to tetragonal distortions induced by Mn2+ at Ga sites, and the demagnetizing effects due to formation of ferromagnetism (FM) Mn-clusters. © 2008 Elsevier B.V. All rights reserved.