Electron spin resonance spectral parameters of V^{4+} ions in vanadate-lithium-borate glasses have been calculated by the crystal-field theory. The theoretical results are g_{∥ } = 1.940, g_{⊥} = 1.983 and A_{∥ } = -175×10^{-4} cm^{-1}, A_{⊥} = -65×10^{-4} cm^{-1} which are good agreement with the experimental values (g_{∥ } = 1.939(3), g_{⊥} = 1.998(3) and A_{∥ } = (170.6-176.4)×10^{-4} cm^{-1}, A_{⊥} = (61.3-71.4)×10^{-4} cm^{-1}). In addition, the bond lengths of the local lattice structure are, respectively, R_{∥ } = 1.5 Å and R_{⊥} = 1.95 Å which have been shown to have a compressed tetrahedral geometry along the C_4 axis.
In the present work, software for exit electron wave reconstruction based on the iterative approach was implemented and a new method for drift-correction of the focal series was proposed.
Magnetooptical properties of (Ga,Fe)N layers containing various concentrations of Fe-rich nanocrystals embedded in paramagnetic (Ga,Fe)N layers are reported. Previous studies of such samples demonstrated that magnetization consists of a paramagnetic contribution due to substitutional diluted Fe ions as well as of ferromagnetic and antiferromagnetic components originating from Fe-rich nanocrystals, whose relative abundance can be controlled by the growth conditions. The nanocrystals are found to broaden and to reduce the magnitude of the excitonic features. However, the ferromagnetic contribution, clearly seen in SQUID magnetometry, is not revealed by magnetic circular dichroism. Possible reasons for differences in magnetic response determined by magnetic circular dichroism and SQUID measurements are discussed.
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