The authors demonstrate multiple reference source Fourier transform holography with soft x rays. This technique extends the detection limit of high resolution lensless imaging by introducing spatial multiplexing to coherent x-ray scattering. In this way, image quality is improved without increasing the radiation exposure to the sample. This technique is especially relevant for recording static images of radiation sensitive samples and for studying spatial dynamics with pulsed light sources. Applying their technique in the weak illumination limit they image a nanoscale test object by detecting ∼2500 photons. The observed enhancement in the signal-to-noise ratio of the image follows the square root of the number of reference sources.

Using a combination of synchrotron radiation based magnetic imaging and high-resolution transmission electron microscopy we reveal systematic correlations between the magnetic switching field and the internal nanoscale structure of individual islands in bit patterned media fabricated by Co/Pd-multilayer deposition onto pre-patterned substrates. We find that misaligned grains at the island periphery are a common feature independent of the island switching field, while irregular island shapes and misaligned grains specifically extending into the center of an island are systematically correlated with a reduced island reversal field.

We demonstrate phase imaging by means of resonant soft x-ray holography. Our holographic phase-contrast method utilizes the strong energy-dependence of the refractive index at a characteristic x-ray absorption resonance. The general concept is shown by using a Co/ Pd multilayer sample which exhibits random nanosized magnetic domains. By tuning below the Co Ledge resonance, our quantitative and spectroscopic phase method allows high-contrast imaging of nanoscale electronic and magnetic order while increasing the probing depth and decreasing the radiation dose by an order of magnitude. The complex refractive index is quantitatively obtained through the interference between resonant and nonresonant scattering.

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