THE LARGER POLAR KERR ROTATION OF FE-SI ALLOY-FILMS AND THEIR MAGNETIC-PROPERTIES

The structure, magnetic properties and polar Kerr effects of Fe100-xSi x (0 less than or equal to x less than or equal to 70) alloy films pre pared by ion-beam co-sputtering were studied. We find that the saturat ion magnetization of these films decreases with increasing x, and a pl ateau of constant magnetization occurs as 22 less than or equal to x l ess than or equal to 28. Their polar Ken rotation theta(k) decreases w ith increasing x as x less than or equal to 16.2 and x greater than or equal to 30, but increases with increasing x as 20 less than or equal to x less than or equal to 28. In the measuring wavelength range of 4 00-800 nm, the theta(k) of Fe72Si28 film is 40% to 50% larger than tha t of pure Fe film. We think that amorphization may play an important r ole in enlarging the polar Kerr rotation of these films. (C) 1998 Amer ican Institute of Physics.