Polarization-modulated magnetic soft-x-ray transmission microscopy

Abstract

An adjustable aperture element has been integrated into the full-field soft-x-ray microscope at the Advanced Light Source to select either the right or left elliptically polarized x rays emitted at an inclined angle from a bending magnet. Magnetic contrast recorded at the Fe L-3 edge in a 59-nm-thin Gd25Fe75 layer can be modulated and scales with the degree of circular polarization in agreement with theoretical calculations. Nonmagnetic background contributions can be reduced and magnetic contrast is enhanced by comparing two images taken with opposite circular polarization. The fast modulation speed of this technique allows for lock-in recording schemes in high-resolution magnetic soft-x-ray microscopy.