NONLINEAR RESPONSE OF ANTIFERROMAGNETIC FILMS TO RADIATION AT OBLIQUE-INCIDENCE

The response of an antiferromagnetic film to incident radiation at obl ique incidence is studied in the nonlinear regime. For given values of the frequency and incidence angle, the reflectivity of a film of arbi trary thickness is obtained as an implicit function of the incident fi eld amplitude. The compound effect of the incidence angle and field st rength on the reflected radiation is studied by means of the analysis of the reflection coefficient calculated for different values of these external variables. We use the physical parameters of the uniaxial He isenberg antiferromagnet FeF2 to obtain numerical results. It is found that the threshold for nonlinear optical behavior is strongly depende nt on the incidence angle.