2001/02/13 by Peter Johansson, S. Peter Apell, D. R. Penn
Physics and Astronomy · #cond-mat
paper · pdf · doi:10.1103/physrevb.64.054411
published as Phys. Rev. B 64, 054411 (2001). · 17 pages, 8 figures
arxiv created 2001/02/13 · arxiv updated 2009/11/30
We propose a theory for a type of apertureless scanning near field microscopy that is intended to allow the measurement of magnetism on a nanometer length scale. A scanning probe, for example a scanning tunneling microscope (STM) tip, is used to scan a magnetic substrate while a laser is focused on it. The electric field between the tip and substrate is enhanced in such a way that the circular polarization due to the Kerr effect, which is normally of order 0.1% is increased by up to two orders of magnitude for the case of a Ag or W tip and an Fe sample. Apart from this there is a large background of circular polarization which is non-magnetic in origin. This circular polarization is produced by light scattered from the STM tip and substrate. A detailed retarded calculation for this light-in-light-out experiment is presented.