Magnetic circular dichroism in photoemission from rare earth materials: a new technique in surface and thin-film magnetism

Using circularly polarized X-rays to excite photoelectrons from magnetically ordered rare-earth materials gives rise to large magnetic circular dichroism in photoemission (MCD-PE), i.e. the intensity of 4f-photoemission lines strongly depends on the orientation of sample magnetization with respect to the photon spin. To explore its potential for application as near-surface magnetometer with atomic-layer resolution, we studied MCD-PE at the (0001)-surfaces of Gd and Tb where the magnetization of the topmost atomic layer-by help of the surface core-level shift-is spectroscopically separated from the bulk magnetization. In thin films containing different rare earths MCD-PE allows to monitor the magnetization in an element specific way. This is demonstrated using the ordered heteromagnetic interface Eu/Gd as an example.