Embedded iron nanoclusters prepared by Fe ion implantation and GMR property

Magnetization and magnetoresistance were studied in iron-ion-implanted aluminum oxide crystals. The implantation was done to a dose of 2/spl times/10/sup 17/ ions/cm/sup 2/ with ion energy of 100 keV. We have observed a magnetoresistance ratio of 6.0% at the field of H=12 kOe. Conversion electron Mossbauer spectroscopy and magnetization measurement show that most of the implanted ions precipitate as /spl alpha/-Fe clusters with a few nm size in radii; the spectra reveals clusters in both superparamagnetic and ferromagnetic states. To study the process of the nanocrystalline formation /sup 57/Fe ions as Mossbauer probes were partially implanted at a fluence of 2/spl times/10/sup 17/ ions/cm/sup 2/.