Papers by Keyword: Magnetic Circular Dichroism

Abstract: Morphology, structure, magnetic properties and magnetic circular dichroism (MCD) were studied for the Fe_xS_y and Fe_xSe_y nanoparticles (NPs) synthesized with the polyol mediated and the thermal decomposition processes, correspondingly, at different regimes. For all NPs samples, but Fe₃S₄, MCD was measured for the first time. It has been shown that in the case of sulfides, the character of the MCD spectrum changes as the NPs phase composition transforms from Fe₃S₄ to FeS with the synthesis temperature increase. At the same time, the shape of the MCD spectrum is almost independent of the NPs phase in the case of iron selenides

Abstract: GaMnAs layers fabricated on GaAs(001) substrates by laser ablation technique were studied using the magneto-optical transversal Kerr effect (TKE) (E = 0.5 - 4.0 eV) and spectral ellipsometry (E = 1.4 - 4.5 eV). Obtained spectral, temperature and magnetic field TKE dependences shown that the used technique allowed us to obtain ferromagnetic (Ga,Mn)As layers, whose composition was close to single-phase one (without MnAs inclusions). Spectral dependences of the off-diagonal components (e’ = e’₁ - ie’₂) of the permittivity tensor and also of the magnetic circular dichroism (MCD) were calculated for ferromagnetic (Ga,Mn)As sample. The calculated dependences were compared with the published magneto-optical spectra of (Ga,Mn)As layers grown by molecular beam epitaxy.

Abstract: Optical and magneto-optical spectra in transmission and reflection and their features for microcavity one-dimensional magnetophotonic crystals with double layer bismuth-substituted iron garnet films are considered. At the first presented the experimental results of magnetic circular dichroism investigations in microcavity one-dimensional magnetophotonic crystals.

Abstract: Co and Ni nanoparticles were fabricated in fused silica plates by ion implantation technique. Electron microscopy showed the nanoparticles to be of spherical shape. Magnetic circular dichroism (MCD) was investigated in the spectral range 1.2 - 4.2 eV in a field of about 3 kOe. MCD spectra are considerably different from the spectra of thin nickel and cobalt films. MCD spectra for Ni nanoparticles are associated with surface plasmon resonance.

Abstract: The absorption and magnetic circular dichroism spectra of f-f transitions 6H15/2 → 6F3/2, 6F5/2 , 6(F7/2 +H5/2) and 6(F9/2+H7/2) in Dy3+ ion were studied in the glasses: Dy2O3-P2O5-SiO2-GeO2 and Dy2O3-La2O3-Al2O3-B2O3-SiO2-GeO2 with different concentrations of Dy3+ ions in temperature range 100-300 K. Basing on this data, absolute values and temperature dependences of the paramagnetic magneto-optical activity (MOA) of the transitions were determined. The origin of the MOA of f-f transitions was analyzed with the help of two models. In the first model, MOA is considered as a consequence of admixture of states with opposite parity by odd components of crystal field. The second approach is based on the Judd-Ofelt theory. The same f-f transitions reveal different values and temperature dependences in different glasses, what testifies to a different symmetry of the nearest environment of Dy3+ ions in these glasses.

Abstract: Faraday rotation (FR) and magnetic circular dichroism (MCD) of nanocomposite structures based on potassium-aluminum-germanium-boron glasses co-doped with Fe and rare earth (RE) or Y+Bi oxides have been studied. Formation of magnetic nanoparticles as a result of the glass heat treatment ensures them magnetic and magneto-optical properties typical of magnetically ordered substances. At the same time, glasses keep transparence in visual spectral range owing to low paramagnetic oxides concentration. FR and MCD spectra of the heat treated glasses are shown to be very close to those of γ-Fe2O3 and practically independent of the RE element nature for the light wave energies lower than 22000 cm-1. For higher energies, the MCD spectrum shape depends strongly on RE what evidences the different origin of magneto-optical effects in two spectral ranges.

Abstract: Nano-composite structures based on potassium-aluminum-germanium glasses doped simultaneously with Fe and rare earth (RE) oxides - Gd, Tb, Dy, Ho, or Yb were studied for the first time. Samples were fabricated by glass technology and subjected to an additional thermal treatment at different regimes. Formation of magnetic nanoparticles was revealed with transmission electron microscope. Morphology and space distribution of nanoparticles in the glasses as well as optical and magneto optical spectra have been shown to be dependent on the additional treatment regime and almost independent of the type of the rare earth element.