Key words europium-doped lithium yttrium fluoride, Bridgman-Stockbarger growth, X-ray photoelectron spectroscopy, valence instability of europium. PACS 71.20. Ps, 73.20.At, 75.20.Ck, 81.10.Fq, 82.30.Lp LiY 1-x Eu x F 4 (x = 0; 0.1 nominally) crystals were obtained by a modified Bridgman-Stockbarger technique. Europium was found to coexist in the LiYF 4 :Eu crystal in two valence states, Eu 3+ and Eu
2+, the content of the latter being enhanced in the near-to-surface region. The presence of bulk divalent europium is attributed to a partial reduction of europium during crystal growth. Because of the presence of Eu 2+ , additional electronic states in the electronic gap of LiYF 4 were observed.
Articles you may be interested inVisualization of vortex motion in FeAs-based BaFe1.9Ni0.1As2 single crystal by means of magneto-optical imagingWe report on optimizing the magneto-optical ͑MO͒ response of dielectric/Fe/dielectric sandwich structures for microwave B-field sensor applications. We have performed experimental MO spectroscopic and simulation studies of FeF 2 / Fe/ FeF 2 sandwiches with varying both top and bottom FeF 2 layer thicknesses. We evaluate the performance of the sensor with MO figure of merit ͑off-diagonal reflection coefficient͒ rather than with MO polarization state ͑MO azimuth rotation and ellipticity͒. Our simulations indicate that an increase in the modulus of the MO signal by a factor of 17 is feasible compared to the bulk Fe. However, the corresponding enhancement of the figure of merit, which is the relevant parameter, is only threefold. These simulations were carried out for the operating wavelength of sensors at 810 nm. We show, contrary to the general belief, that in order to enhance the MO performance of the sensor it is more important to optimize the bottom dielectric layer rather than the top layer.
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