Magnetic circular dichroism in cobalt films observed with scanning-tunneling-microscope-excited fluorescence

We report on experiments showing that magnetism can be probed by means of the circular polarization of the fluorescence that is excited when charge carriers are injected into a magnetic surface with the tip of scanning tunneling microscope. We attribute this result to the interplay of the spin-orbit and the exchange interactions which gives rise to coupling between the electron-spin polarization of the valence bands of the ferromagnet and the photon spin. © 1994 The American Physical Society.