Magnetic imaging with soft x-ray spectroholography

We present recent advances in imaging magnetic nanostructures via lensless holographic x-ray techniques. In addition to the tunable energy and polarization this method also uses the coherent photon flux that is now available at third generation synchrotron radiation sources. Our spectroscopic imaging technique is based on the direct Fourier inversion of a holographically formed interference pattern, thus we refer to it as spectroholography. By exploiting the magnetic dichroism in resonance at the L-3 absorption edges of the magnetic transition metals (wavelength of similar to 1-2 nm and energy of similar to 700-900 eV), images of magnetic nanostructures have been obtained with a spatial resolution below 50 nm. Using Si3N4-membrane substrates we combine in our experimental setup the sample itself rigidly with the holographic mask structure consisting of an 800 nm gold layer with a micronsized object aperture and a nanosized reference hole on the backside of the membrane. Such a compact implementation leaves plenty of space for installing extreme sample environments such as high magnetic fields and low temperatures that are difficult to combine with conventional x-ray imaging techniques based on focusing optics. (C) 2006 American Institute of Physics.