OBSERVATION OF THE TRANSVERSE 2ND-HARMONIC MAGNETOOPTIC KERR-EFFECT FROM NI81FE19 THIN-FILM STRUCTURES

We report second-harmonic magneto-optic Ken measurements on air-expose d, polycrystalline Ni81Fe19 thin films, ranging in thickness from 1 nm to 2 mu m, on Al2O3 coated Si (001). For samples thicker than 20 nm, in the transverse Ken geometry, we observe a factor of 4 change in sec ond-harmonic intensity upon magnetization reversal. For thin samples, we observe interference between second-harmonic fields from the variou s interfaces and deterioration of ferromagnetism in the 1 and 2 nm fil ms. Modeling suggests that the Ni81Fe19/Al2O3 interface has a larger s econd-order susceptibility than the air/Ni81Fe19 surface. (C) 1996 Ame rican Institute of Physics.