Variation of longitudinal kerr and faraday effects with angle of incidence in thin iron films

Abstract

Longitudinal Kerr and Faraday effects and associated optics of thick and thin iron films sputtered on glass slides and half-cylindrical prisms have been measured as a function of the angle of incidence with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</tex> polarization occurring at a wavelength of 6328 Å It was shown that a simple two-surface thin-film model correctly predicts the large differences observed between Faraday <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</tex> rotations of an 800 Å film measured through the front and back of a glass slide ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\approx 2x</tex> ) and through the glass side ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\approx 7x</tex> ) at a 75° angle of incidence for identically optical paths. These differences result from the nonequivalent transmission coefficients for opposite propagation directions. In addition, the phenomenological model provided reasonable agreement with the observed deep minimum of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</tex> reflectivity (0.05 percent) near 69° incident angle and the correspondingly large optically-enhanced maximum of the Kerr <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</tex> rotation (-5.3°) near 71° incident angle for an approximate 200 Å film deposited on the hypotenuse of a half-cylindrical prism. In order to achieve satisfactory theoretical agreement with these Kerr and Faraday measurements, it was absolutely necessary to take into account the nonlinear dependence of the complex index of refraction of thin iron films on thickness.