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# Simulated normalised magnetisation of field cooled (FC) and zero field cooled (ZFC) magnetic moments of nanoparticle ensembles with different standard deviations of log-normal volume distribution.

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X-ray absorption spectroscopy facilitated by state-of-the-art synchrotron radiation technology is presented as a powerful tool to study nanoscale systems, in particular revealing their static element-specific magnetic and electronic properties on a microscopic level. A survey is given on the properties of nanoparticles, nanocomposites and thin film...

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... Magnetic anisotropy energy (MAE) dependence on particle's volume leads to superparamagnetic effect due to which magnetisation starts fluctuating. The temperature at which magnetisation fluctuation occurs is called blocking temperature [5]. Literatures do not provide any standard procedure to deduce blocking temperature for nanoparticles. ...
... Literatures do not provide any standard procedure to deduce blocking temperature for nanoparticles. Antoniak [5] referred inflection point temperature in ZFC as the θB. Presa et al. [6] represented temperature corresponding to maximum ZFC magnetization as θB for γ-Fe2O3 nanoparticles. ...
... By sliding the magnetic arrays against each other, different types of linear and circular polarization can be obtained. Figure adapted from[142]. ...
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For more than 40 years, most astrophysical observations and laboratory studies of two key soft X-ray diagnostic 2p-3d transitions, 3C and 3D, in Fe XVII ions found oscillator-strength ratios f3C/ f3D disagreeing with theory. This discrepancy hampered the proposed plasma diagnostic utility based on the observed intensity ratios ever since. In previous laboratory measurements, the ratio was determined by scrutinizing the photon emission of an electron-impact excited plasma. First X-ray laser spectroscopy experiments at a free-electron laser (FEL) confirmed the discrepancy between experiments and theory independently of electron-excitation cross sections that could have falsified previous laboratory measurements. In this thesis, the 3C/3D oscillator-strength ratio was measured by resonantly exciting the transitions utilizing highly brilliant and monochromatic X-ray synchrotron light. Thereby, two proposed systematical effects that could have lowered the results of the FEL measurements were excluded. The final result f3C/ f3D = 3.51(7) of this work is in excellent agreement with the newest state-of-the-art theoretical predictions and appears to finally resolve the long-lasting conundrum. Additionally, for the first time, the individual natural linewidths of lines 3C and 3D, among others, were determined with an uncertainty of � 15%. The findings of this thesis now allow the observed intensity ratios of 3C and 3D to enable their usefulness in the diagnostics of astrophysical spectra.
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... (a) the temperature (T B ) at which the maximum of ZFC magnetization occurs [46,47] (see also inflection-point criterion) [48] and [41,[49][50][51][52]), is already determined in Sect. 4.2 above; (b) the average blocking temperature 〈T B 〉, above which the coercive field and remanent magnetization vanish, is estimated by the expression for the temperature dependence of the coercive fields, as follows [53,54]. ...
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... Due to the static magnetic field lines between the opposite magnets, the electrons are forced to follow oscillating paths and as a result, emit radiation. The interference of the radiation of different magnets results in a spectrum with quasi-monochromatic peaks [115]: ...
... circularly polarized x-rays by a shift of λ U /4. Similarly, the left circularly polarized x-rays can be tuned by a shift of −λ U /4. For details, see [113,115] and [26]. can be tuned by a grating unit via Bragg's law [41]: ...
... A fourth possible case of left circularly polarized x-ray is not shown here. Taken from[115]. ...
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... Since the tip is located in the far-field, i.e., it is not in the electron tunneling distance, the current increase is caused by the electrons emitted from an ensemble average of Co on the surface. Such current versus energy (I-E) spectroscopy is related to the X-ray-absorption cross section of the material, and it is akin to conventional X-ray absorption spectroscopy (XAS) 9,18 except that an SX-STM tip is used here as a local detector. ...
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