Abstract

Recently we developed the theory of long-range surface magnetoplasmons propagating along a thin magnetic metal film bounded by nonmagnetic dielectrics in the presence of a transversely applied magnetic field. Experimental verification of the theory was obtained by measuring the transverse Kerr reflectance from prism-coupled modes in thin nickel films. The narrow resonance of the long-range mode makes it highly sensitive to the magnetic properties of metal surfaces compared to other optical techniques. We analyze the response of four measurement geometries to a thin magnetic metal film with a surface whose magnetooptic coefficient differs from that of the rest of the film. Kerr reflectance in our geometry is more sensitive to surface magnetooptic properties than the Otto or Krestchmann geometries or reflectance from bare nickel films. Experimental studies of nickel films guiding long-range surface magnetoplasmons indicate a magnetically inert surface layer of 1-nm thickness. We believe that this layer is due to the absorption of organic coupling fluid. Other possible explanations, such as an oxide layer or surface roughness, do not agree with the measurements.

© 1987 Optical Society of America