TUNNELING GIANT MAGNETORESISTANCE IN FE-SIO2 MULTILAYERED AND ALLOYEDFILMS

Magnetic properties and magnetoresistance (MR) are examined for Fe-SiO 2 multilayers and granular films prepared on glass substrates by rf sp uttering. In both the multilayers with thin Fe layers, which are disco ntinuous forming Fe granules, and the granular films of small Fe compo sition, the magnetization curve follows the Langevin function indicati ng superparamagnetic nature. These films exhibit the giant MR arising from spin-dependent tunneling between neighboring superparamagnetic Fe granules for both systems, and show a maximum value of 3.6% at room t emperature.