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| Home > Publications database > Combining resonant inelastic X-ray scattering with micrometer resolution to image electronic properties of quantum materials |
| Master Thesis | PUBDB-2019-04127 |
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2019
Abstract: This thesis presents developments and results of an experimental setup which combines soft X-ray spectroscopy methods for electronic structure analysis and imaging capabilities with the goal to gain detailed understanding of quantum materials, which exhibit spatial electronic inhomogeneities. The setup features a combination of two Fresnel zone plates which are about 1mm long and sub-μm wide: Firstly, a linear illumination zone plate creates a vertical X-ray focus line on the sample. Secondly, an off-axis zone plate, located between the sample and the two-dimensional detector, disperses X-rays emitted from the sample in horizontal direction, while also imaging the sample onto the detector at the same time. In this way, a 2D map is created on the detector which, in the vertical dimension, contains information on the position on the sample from where the X-rays are emitted, and in the horizontal dimension resolves the photon energies emitted from the sample. The presented experiment was performed at the soft X-ray beamline P04 of the synchrotron radiation source PETRA III at the DESY research facility in Hamburg. In the first part of the experiment, the spatial resolution of the setup was determined to be better than 3 μm. Secondly, this spatial resolution was combined with X-ray absorption (XAS) and resonant inelastic X-ray scattering (RIXS) measurements at the oxygen Kedge to investigate the insulator-to-metal phase transition of VO2 microsquares with an edge length of 30 μm. These structures were studied, in order to answer the question if the phase transition behaviour is different in structured parts of a sample, where the defect density at the edges of structures may act as nucleation centres. This is compared to the central area of the squares acting as a model for a bulk material reference. This is an important step towards functionalising phase transitions in complex materials, where insights from bulk materials may not readily be transferred to structured devices.
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