Structural and magnetic properties of Fe ion implanted Al2O3

The structural and magnetic properties of Fe-Al2O3 films; which have been p repared by implantation of 100 keV Fe-56 and/or Fe-57 ions into single crys tals of alpha-Al2O3 to a dose of 1x10(17) ions/cm(2), have been investigate d by conversion electron Mossbauer spectroscopy at room temperature (RT). T he magnetoresistance (MR) is also measured by a two-terminal method at RT a nd the MR ratios are obtained from 7% to 8.5%, which are about two times la rger than the MR ratios of films prepared by sputtering. The MR ratio incre ases on annealing. Magnetization curves measured with a vibrating sample ma gnetometer show the nonhysteresis and unsaturation, namely the superparamag netic nature. We have prepared granular Fe-Al2O3 films having the high MR r atio have been prepared for the first time by Fe ion implantation technique . (C) 1999 Elsevier Science B.V. All rights reserved.