Quantitative determination of the local Kerr rotation by scanning near-field magneto-optic microscopy

By using a polarization-modulation technique in combination with reflection-mode scanning near-field optical microscopy we are able to determine quantitatively the local polar Kerr rotation on thin magnetic films. As an example. the magneto-optic contrast of magnetic domains thermomagnetically written on a Co/Pt sample is discussed. The size of the magnetic domains is 3 x 0.5 mu m(2) and the angular resolution of the local Kerr rotation is better than 0.1 degrees. This measurement technique will make it possible io investigate, e.g., the fine structure of domain walls by scanning near-field optical microscopy. (C) 1998 American Institute of Physics.