THE MAGNETIC PROPERTIES AND TUNNELING MAGNETO-RESISTANCE EFFECT IN Fe-SiO₂ GRANULAR FILMS

Fe-SiO₂ granular films with various fraction of metal volume f_υ were prepared by rf co-sputtering method.X-ray diffraction,transmission electron m icroscopy,Mǒssbauer spectroscopy,vibrating sample magnetometer and resistivity measurements were used to investigate the structure,magnetic properties and tunn eling magnetoresistance （TMR）.It was found that the TMR reached a maximum of 3.3% at f_υ =0.33 and the film appeared superparamagnetism at room temperature.The results of Mǒssbauer spectra recorded at various temperatures indicated that th e size distribution of granule followed the lognormal distribution.The metal Fe composition dependent of TMR in Fe-SiO₂ films was also discussed.