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4.3 Nanoscale Samples and Optics
Project coordinator(s): D. Engel

Project Goals

The new application lab for Nanoscaled Samples and Optics allows to fabricate and characterize a variety of structures to support different experiments. Thin film samples are prepared via magnetron sputter deposition. In close collaboration with the ZELMI at the TU Berlin, nano-structuring of samples before or after the deposition procedure by masking, lithography or via Focused Ion Beam (FIB) is carried out. Additionally we can modify the magnetic properties of multilayer systems by ion implantation. The topographical and magnetic characterization is done by Atomic- and Magnet Force Microscopy (AFM/MFM) and with a Kerr Magnetometer (MOKE).

1) Functional magnetic nanoscaled layer systems

  • Magnetic multilayer
    The variation of the thickness and the material composition of one layer, together with the number of repetition in a stack influence strongly the magnetic properties (e.g. domain size, domain wall size, anisotropies etc.).
    CoPt layer systemCoPt MFM

  • Amorphous RE/TM ferrimagnetic alloys and multilayer
    Ferrimagnetic systems can be tuned via several parameters: exchange coupling, spin-orbital interaction, magnetocrystalline anisotropy, magnetization and compen-sation temperature. The interaction with light depends on these parameters.
    GdFe alloy

  • Exchange bias and spin valve systems
    Variation of materials and layer thicknesses together with applied magnetic field during fabrication for coupling optimization.

Objective: Fabrication of optimized functional magnetic thin layer systems required in the scientific projects at the MBI.

2) Optical elements for XUV and soft x-rays

  • Gratings and Fresnel zone plates for fluence monitoring and optimization
    Curved gratings tailored for the scattering signature of the investigated samples.
    Segmented gratings for beam alignment and profiling.

    FEL mask
    A solid-state thin film sample on a supporting membrane is illuminated by a FEL beam. The grating
    (marked green) scatters into two distinct areas that don’t overlap with the scattering of the sample (blue).

  • Masks for holography imaging
    Focussed Ion Beam (FIB) modification is used to fabricate tailored object and reference holes in a gold film.
  • Modification of various substrate types for imaging and spectroscopy
    Back-thinning allows preparation of thin film samples grown on bulk substrates.
    Enable XUV transmission studies of epitaxially grown thin films.

Objective: Development of optical elements and substrates for single- and multi-shot experiments optimized for FEL and HHG sources.

3) Nanoscale control of magnetic order

  • Design of plasmonic nanostructures
    HU-MBI group (Prof. K. Busch) calculates and designs plasmonic structures to obtain a localized field enhancements for efficient pumping.
  • Fabrication of plasmonic tructures by lithography or FIB
    A complex lithography procedure for the magnetic multilayer samples, sputtered on membrane substrates, is used to fabricate the designed plasmonic structures (without changing the magnetic behavior).
  • Optimization of the design of plasmonic nanostructures
    A close collaboration between the theory and experiment side enables the opti-mization of these nanostructure patterns.

Objective: Design and engineering of plasmonic nanostructures on top of magnetic thin film systems to control the time scale and the spatial confinement of optically manipulated magnetic order.