ABSTRACT
The mechanical setup of a novel scanning reflection X-ray microscope is presented. It is based on zone plate optics optimized for reflection mode in the EUV spectral range. The microscope can operate at synchrotron radiation beamlines as well as at laboratory-based plasma light sources. In contrast to established X-ray transmission microscopes that use thin foil samples, the new microscope design presented here allows the investigation of any type of bulk materials. Importantly, this permits the investigation of magnetic materials by employing experimental techniques based on X-ray magnetic circular dichroism, X-ray linear magnetic dichroism or the transversal magneto-optical Kerr effect (T-MOKE). The reliable functionality of the new microscope design has been demonstrated by T-MOKE microscopy spectra of Fe/Cr-wedge/Fe trilayer samples. The spectra were recorded at various photon energies across the Fe 3p edge revealing the orientation of magnetic domains in the sample.
ABSTRACT
Zone plate design and efficient methods for the fabrication of zone plates for extreme ultraviolet (EUV) and soft x-ray applications in a newly developed scanning reflection microscope are presented. Based on e-beam lithography, three types of transmission zone plates with focal lengths between 6 and 15 mm are reported: (i) phase-shifting zone plates made by 190 nm thick PMMA rings on Si3N4 membranes, (ii) absorbing zone plates made by 75 nm thick Au ring structures on Si3N4, and (iii) freestanding Au rings of 50 nm thickness and increased transmission in the EUV range. Experiments at the DELTA synchrotron facility reveal a minimum spot size and resulting spatial resolution of 9±3 µm, which is the theoretical limit resulting from the synchrotron beam parameters at 60 eV photon energy. Images of a Ti/Si chessboard test pattern are recorded exploiting the energy dependence of the element-specific reflectance.
ABSTRACT
An ultra-high vacuum compatible multipurpose chamber for magneto-optical reflection and transmission experiments with polarization analysis on magnetic systems is introduced. It is applicable in a broad photon energy range from the visible to the soft x-ray regime and for a wide angular range from grazing to normal incidence. It exploits a novel magnetization device based on rotating permanent magnets, which generates tuneable magnetic fields up to 570 mT in longitudinal, transverse and polar geometry. The unique combination of these features enables the feasibility of all typical magneto-optical spectroscopy techniques as T-MOKE, L-MOKE, P-MOKE, x-ray magneto optical linear dichroism, x-ray magnetic circular dichroism in reflection and Kerr polarization-spectroscopy, which is demonstrated for Co with focus on the Co 3p edges.
ABSTRACT
In this paper we describe a novel magnetizing device based on eight rotatable permanent magnets arranged in a quadrupolar configuration, which is termed the TetraMag. TetraMag creates stable and homogeneous magnetic fields at the sample position with a resolution of 0.02 mT tunable between -570 mT and +570 mT. The field direction is continuously rotatable between 0° and 360° within the sample plane, while the field strength is maintained. A simplified mathematical description of TetraMag is developed leading to magnetic field calculations which are in good agreement with the experimental results. This versatile device avoids electrical energy dissipation, cooling mechanisms, and hysteresis effects known from classical electromagnets. It is ultrahigh vacuum compatible and it offers a completely free optical path over 180° for magneto-optical experiments. It is suitable for scattering experiments with synchrotron radiation and neutrons and may be employed in a large class of magnetization experiments.
