Magnetic Domain Imaging of Thin Metallic Layers Using PEEM

Abstract

Photoemission electron microscopy (PEEM) in combination with resonant excitation by circularly polarized soft X-rays has proven to be a powerful analytical tool for the study of magnetic microstructures and multilayers. In this type of electron microscope the lateral intensity distribution of the emitted low-energy secondary or photoelectrons is imaged by an electron-optical system. Owing to its fast parallel image acquisition, its wide zoom range allowing fields of view from almost 1 mm down to a few µm combined with a high base-resolution of the order of 20 nm, the method offers a unique access to many aspects in surface and thin film magnetism on the mesoscopic length scale. Magnetic contrast is achieved by the magnetic circular or linear dichroism. Sum-rule analysis allows to extract quantitative information about the spin and orbital magnetic moments of 3d-transition metals. Two other modes of magnetic imaging via PEEM work with simple UV light sources and are therefore highly attractive for standard laboratory applications. The magnetic stray-field close to the sample surface leads to a Lorentz-type contrast. A third type of contrast arises as a consequence of a small rotation of the displacement vector inside a magnetic material, a phenomenon which is also responsible for the well-known magneto-optical Kerr-effect. Examples and typical applications of magnetic imaging using PEEM are discussed.