Large Faraday rotation (10(5) deg/cm) in Fe-SiO2 granular films made b
y ion-beam sputtering method has been observed at room temperature. Ou
r results show that Faraday rotation (FR) increases with Fe volume fra
ction f(v) and peaks at f(v) approximate to 0.55. This indicates that
Fe granules play an important role in FR of granular materials.