Magnetic asymmetry in photoemission from Fe(100) with linearly polarized synchrotron radiation

We have measured partially angle-integrated photoemission with linearly polarized undulator radiation on the valence band and on the 3p and 3s core levels of iron in an Fe(100) single crystal. A large asymmetry is measured for 3p core levels when reversing the magnetization direction perpendicular to the photoemission plane. A smaller but clear asymmetry is also measured in the valence (3d) band spectrum, and no asymmetry is measured for the 3s core levels. The results are explained by the transverse spin polarization of the near-normal-emission photoelectrons which is induced by the light p polarization and by spin-orbit interaction in the initial state. From the line-shape change of the 3p core level as a function of magnetization reversal the fine structure of the 3p multiplet is derived. This effect provides a very efficient diagnostic of the surface magnetization direction allowing to measure magnetic ordering at surfaces similarly to the Kerr effect, but in a chemically specific and intrinsically surface sensitive way as shown by examples on ferromagnetically coupled and antiferromagnetically coupled Fe/Cr interfaces.