Lensless imaging of magnetic nanostructures by X-ray spectro-holography

Journal name:
Nature
Volume:
432,
Pages:
885–888
Date published:
DOI:
doi:10.1038/nature03139
Received
Accepted

Our knowledge of the structure of matter is largely based on X-ray diffraction studies of periodic structures and the successful transformation (inversion) of the diffraction patterns into real-space atomic maps. But the determination of non-periodic nanoscale structures by X-rays is much more difficult. Inversion of the measured diffuse X-ray intensity patterns suffers from the intrinsic loss of phase information1, 2, and direct imaging methods are limited in resolution by the available X-ray optics3. Here we demonstrate a versatile technique for imaging nanostructures, based on the use of resonantly tuned soft X-rays for scattering contrast and the direct Fourier inversion of a holographically formed interference pattern. Our implementation places the sample behind a lithographically manufactured mask with a micrometre-sized sample aperture and a nanometre-sized hole that defines a reference beam. As an example, we have used the resonant X-ray magnetic circular dichroism effect to image the random magnetic domain structure in a Co/Pt multilayer film with a spatial resolution of 50nm. Our technique, which is a form of Fourier transform holography, is transferable to a wide variety of specimens, appears scalable to diffraction-limited resolution, and is well suited for ultrafast single-shot imaging with coherent X-ray free-electron laser sources4.

At a glance

Figures

  1. Scheme of the experimental set-up.
    Figure 1: Scheme of the experimental set-up.

    Monochromatized and circular polarized X-rays are incident on a mask–sample structure after spatial coherence filtering. The object and reference beam are defined by the mask, and the resulting hologram is recorded on a CCD detector. The lower inset shows the geometry and an electron microscopy image of the mask–sample structure. The scale bar in the microscopy image is 2.0µm. The top inset shows a STXM image of the magnetic structure illuminated through the sample aperture. The field of view is 1.5µm.

  2. Hologram recorded with X-rays (right circular polarization) at a wavelength of 1.59[thinsp]nm.
    Figure 2: Hologram recorded with X-rays (right circular polarization) at a wavelength of 1.59nm.

    The maximum in-plane momentum transfer in the measurement is ± 0.13nm-1, shown up to ± 0.06nm-1 in the image. Intensity is represented on a logarithmic grey scale, with black denoting the minimum intensity of 103 and white denoting the maximum intensity of 105. Black and white appear saturated in the picture only, the dynamic range of the hologram is 107.

  3. Images retrieved from the hologram.
    Figure 3: Images retrieved from the hologram.

    a, Two-dimensional fast Fourier transformation of the hologram in Fig. 2. b, Zoomed-in image, obtained by subtracting the Fourier transformations of opposite-helicity holograms. Below are shown scan lines through the holographic image (red) and the STXM image in Fig. 1 (blue).

Author information

Affiliations

  1. BESSY mbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany

    • S. Eisebitt,
    • M. Lörgen,
    • O. Hellwig &
    • W. Eberhardt
  2. SSRL, Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, California 94025, USA

    • J. Lüning,
    • W. F. Schlotter &
    • J. Stöhr
  3. Department of Applied Physics, 316 Via Pueblo Mall, Stanford University, Stanford, California 94305-4090, USA

    • W. F. Schlotter
  4. San Jose Research Center, Hitachi Global Storage Technologies, 650 Harry Road, San Jose, California 95120, USA

    • O. Hellwig

Competing financial interests

The authors declare no competing financial interests.

The authors declare that they have no competing financial interests.

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