Theory of magnetic surface microscopy

Light is produced when a scanning tunneling microscope is used to probe a metal surface. Recent experiments on cobalt utilizing a tungsten tip found that the light is circularly polarized; the sense of circular polarization depends on the direction of the sample magnetization, and the degree of polarization is of order 10%. This raises the possibility of constructing a magnetic microscope with very good spatial resolution. For iron and cobalt we find a degree of polarization of order 0.1%. This is in disagreement with the experiments on cobalt as well as previous theoretical work, which found order of magnitude agreement with the experimental results. However, a recent experiment in the Electron Physics Group on iron showed less than a 2% effect. We predict that the use of a silver tip would increase the degree of circular polarization for a range of photon energies.

Circularly Polarized Light Emission in Scanning Tunneling Microscopy of Magnetic Systems


David R. Penn


Peter Apell - Chalmers University of Technology

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Online: May 1996
Last Updated: February 2008

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