Thin Solid Films, Vol.505, No.1-2, 152-156, 2006
Formation of metastable Fe-Cu alloy nanoparticles by ion implantation
The formation of the immiscible Fe-Cu nano-clusters by sequential implantations of Fe and Cu ions in crystalline Al2O3 is reported in this study. The implantation was performed at room temperature to a total dose of 2.0 x 10(17) ions/cm(2), changing the relative dose of Fe and Cu ions to obtain various Cu concentrations. The possibility of the metastable alloy clusters was investigated by a combined measurement of conversion electron Mossbauer spectroscopy, X-ray diffraction, magneto-resistance (MR) and magnetization. It is shown that the additional Cu implantation leads to both the transitions from super-paramagnetic to ferromagnetic states in the iron nano-clusters aggregated beforehand and also the decrease in the internal fields, suggesting the alloy formation. MR ratio has been found to decrease with increasing Cu dose, indicating also the fort-nation of Cu nano-clusters in the matrices. (c) 2005 Elsevier B.V All rights reserved.