A full field transmission X-ray microscope as a tool for high-resolution magnetic imaging

The XM-1 soft x-ray microscope is a user-dedicated facility located at the Advanced Light Source at Lawrence Berkeley National Laboratory and has recently been established as a tool for high-resolution imaging of magnetic domains. It is a conventional full field transmission microscope which is able to achieve a resolution of 25 nm by using high-precision zone plates. It uses off-axis bend-magnet radiation to illuminate samples with elliptically polarized light. When the illumination energy is tuned to absorption edges of specific elements, it can be used as an element-specific probe of magnetism on the 25 nm scale with contrast provided by magnetic circular dichroism. The illumination energy can be adjusted between 250-850 eV. This allows magnetic imaging of elements including chromium, iron and cobalt. The spectral resolution has been shown to be E/DeltaE = 500-700. This spectral resolution allows a high sensitivity so that magnetization has been imaged within layers as thin as 3 mu. Since this is a photon based magnetic microscopy, fields can be applied to the sample even during imaging without affecting the spatial resolution. The current system can apply in-plane or out-of-plane fields of a few kOe.