Wavelength dependence of the magnetic resolution of the magneto-optical near-field scanning tunneling microscope

A magneto-optical near-field scanning tunneling microscope is used to image the prewritten magnetic domain structure of a Pt/Co multilayer. A semiconducting tip acts as a local photodetector to measure the magnetic circular dichroism signal coming from the magnetic sample. The resolution of the magnetic imaging is given by the photoelectrically active volume of the tip. Reduction of the laser light wavelength resulted in a factor of 4 improvement of the magnetic resolution. Based on a sound and applicable definition we estimate the resolution to be (60+/-35) nm for a wavelength of 532 nm. (C) 1998 American Institute of Physics. [S0003-6951(98)04044-3]