Spin-sensitive magnetic microscopy with circularly polarized X-rays

Abstract
X-ray dichroism microscopy is a new method for microscopic mapping of magnetic domains at surfaces, that measures the local magnetic moment and magnetization direction of individual elemental constituents of the sample. In addition, it is able to probe the magnetic properties of layers buried as much as 100Å below the surface. The method uses the magnetic X-ray dichroism effect, in combination with the X-ray photoelectron emission microscope (X-PEEM), also called the X-ray secondary electron microscope (XSEM). The X-PEEM has already been shown to be a valuable tool for small-area X-ray absorption fine-structure (XAFS) spectroscopy, and for state-selected imaging. In this paper, the principles involved in imaging magnetic domains using the X-ray photoelectron emission microscope are discussed, based on recent results with circularly polarized soft X-rays. Examples of applications of the technique are reviewed, including direct mapping of the oscillatory exchange coupling in transition metal sandwich structures, and imaging of recorded bit patterns in magnetic media.