Energy difference between the ferromagnetic and antiferromagnetic collinear orderings has been ca... more Energy difference between the ferromagnetic and antiferromagnetic collinear orderings has been calculated for the uniform and dimer Mn-pair geometries in order to find the ground state distribution of the Mn atoms in InAs host. We find the preference of the dimer ferromagnetic configuration of Mn dopants and an importance of optimizing the atomic site positions. The frequency-dependent optical and magneto-optical properties, namely the dielectric tensor (on-and off-diagonal components), the electron energy loss spectra, and the transversal Kerr effect (TKE), are calculated. Calculated TKE resonance in In1-xMnxAs (x=0.0625) is found to be in good agreement with corresponding experimental magneto-optical spectra. The origin of the large TKE is discussed.
We present recent experimental results on the structural, electrical, magnetic, and magneto-optic... more We present recent experimental results on the structural, electrical, magnetic, and magneto-optical properties of Mn-implanted Si and Co-doped TiO(2-delta) magnetic oxides. Si wafers, both n- and p-type, with high and low resistivity, were used as the starting materials for implantation with Mn ions at the fluencies up to 5 x 10(16) cm(-2). The saturation magnetization was found to show the lack of any regular dependence on the Si conductivity type, type of impurity and the short post-implantation annealing. According to XMCD Mn impurity in Si does not bear any appreciable magnetic moment at room temperature. The obtained results indicate that above room temperature ferromagnetism in Mn-implanted Si originates not from Mn impurity but rather from structural defects in Si. The TiO(2-delta):Co thin films were deposited on LaAlO3 (001) substrates by magnetron sputtering in the argon-oxygen atmosphere at oxygen partial pressure of 2 x 10(-6)-2 x 10(-4) Torr. The obtained transverse Kerr effect spectra at the visible and XMCD spectra indicate on intrinsic room temperature ferromagnetism in TiO(2-delta):Co thin films at low (< 1%) volume fraction of Co.
We report optical and magneto-optical results as well as atomic force microscopy (AFM) and magnet... more We report optical and magneto-optical results as well as atomic force microscopy (AFM) and magnetic force microscopy (MFM) results for InFeSb samples prepared by laser ablation. AFM and MFM studies have revealed the presence of magnetic particles on the samples surface, whose sizes depend on the Fe content and substrate temperature. It has found that both optical and magneto-optical spectra are superposition of spectra from the doped InFeSb layers and particles on their surface.
Spectral and field dependencies of Transversal Kerr Effect (TKE) for [(Co45Fe45Zr10)Z(Al2O3)100-Z... more Spectral and field dependencies of Transversal Kerr Effect (TKE) for [(Co45Fe45Zr10)Z(Al2O3)100-Z(X)/α-Si:H(Y)] n multilayers have been studied in the energy range 0.5 - 4.0 eV. It was found that TKE field dependencies in the nearest IR energy range exhibit anomalous behavior for structures only with thin Si layers and this behavior vanishes with increasing of the Si layer thickness. TKE spectra measured in small and large magnetic fields were essentially different. It was shown that magneto-optical response of multilayered structure composite-silicon is the sum of contributions from two composites: (Co45Fe45Zr10) - Al2O3 + Si + silicides and (Co45Fe45Zr10) - Si + silicides, which have a different sign of TKE in the nearest IR spectrum and their magnetic states depend both on composite and semiconducting layer thicknesses.
INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005., 2005
The present study addresses the magneto-optical properties of CoX(TiO2)1-X and CoX(Sm2O3)X thin f... more The present study addresses the magneto-optical properties of CoX(TiO2)1-X and CoX(Sm2O3)X thin films in as-deposited state and after annealing. The films are composed of the granular ferromagnet-insulator composites where the nanometer-sized Co are embedded in either TiO2 or Sm2O3 insulating matrix. The magnetic properties of the films were measured by vibrating sample magnetometer (VSM) in magnetic field up to 20
We report magneto-optical spectra of the Heusler bulk alloys Ni-Mn-In, thin films Ni-Mn-Ga, micro... more We report magneto-optical spectra of the Heusler bulk alloys Ni-Mn-In, thin films Ni-Mn-Ga, microwires Ni-Mn-In and Ni-Mn-Ga in martensitic and austenitic states. Transversal Kerr effect (TKE) was studied at an angle of light incidence of 68° with respect to the sample plane, in the energy range 0.5 eV < E < 4.0 eV, at 50 350 K temperatures, and in magnetic fields up to 3.5 kOe. The TKE spectra profile does not change too much at martensitic transformation in Ni2MnGa thin films, only magnitudes of characteristic maxima decrease. The magneto-optical response of Ni2MnGa microwires is very similar to that for Ni2MnGa thin films. For most of studied bulk samples, the TKE signal is very weak (about 10-5), about two orders of magnitude smaller than for thin films, and in many cases could not be detected at all. It indicates the strong dependence of the magneto-optical response of Heusler alloys on the quality of optically or electrochemically polished surfaces and their microstructure.
We demonstrate that the colossal magnetoresistance (CMR) manganites doped with the monovalent cat... more We demonstrate that the colossal magnetoresistance (CMR) manganites doped with the monovalent cations of the large ionic radius A (A=Na+, K+, Ag+) reveal enhanced sensitivity of the electrical resistance to the magnetic field near the room temperature. The main obstacle to their practical application is severe difficulty of the synthesis, in particular, that of the thin films because of the high volatility or low thermal stability of the oxides of these doping elements. But the preparation of the films in two steps allows for the materials with the superior CMR characteristics. At the first step, epitaxial single phase precursor La1−xAyMnO3 (0.3≥x>y) is formed on the single crystal substrate due to the epitaxial stabilization by the single source MOCVD (metalorganic chemical vapor deposition) using thd-complexes. The second step is the isopiestic annealing with the powder mixture determining the high concentration of the volatile oxide in the gas phase resulting in the saturation of La1−xAxMnO3 (x=y) films by the gas phase transport. The film transformations are studied with XRD and HREM. The high magnetoresistance MR and magnetotransmission MT with the linear magnetic field (H) dependence near the room temperature (dMR/dH up to 45%/T, dMT/dH up to 15%/T) are reported.
Combined studies of the impedance and magneto-optical properties of porous silicon-cobalt nanocom... more Combined studies of the impedance and magneto-optical properties of porous silicon-cobalt nanocomposites are carried out. Correlations between the charge transfer over a nanocomposite layer and the spectral response of the transverse Kerr effect are revealed.
Spectral dependences of the transversal Kerr effect (TKE) as well as of the real and imaginary pa... more Spectral dependences of the transversal Kerr effect (TKE) as well as of the real and imaginary parts of the permittivity of InMnAs layers were studied. Pulsed laser ablation of Mn and InAs targets was used to form the layers on GaAs(100) substrates. Spectra of the optical constants and TKE depended substantially on layer fabrication conditions and testified to the presence of MnAs inclusions in the samples. The cross-sectional transmission electron microscopy revealed the presence of inclusions of size 10-40 nm in the layers. At room temperature a strong resonant band was observed in the TKE spectra of the InMnAs layers in the energy range of 0.5-2.2 eV. In this band the TKE was comparable in magnitude but opposite in sign to that in the strong ferromagnetic MnAs. The resonant character of the TKE spectra was explained by excitation of surface plasmons in the MnAs nanoclusters embedded in the InMnAs semiconductor host. Modelling the TKE spectra for (InAs)(1 - X):(MnAs)(X) nanocomposites in the effective-medium approximation (Maxwell-Garnett approximation) confirmed the assumption on the plasmon mechanism of the resonant enhancement of the transversal Kerr effect in the InMnAs layers.
Energy difference between the ferromagnetic and antiferromagnetic collinear orderings has been ca... more Energy difference between the ferromagnetic and antiferromagnetic collinear orderings has been calculated for the uniform and dimer Mn-pair geometries in order to find the ground state distribution of the Mn atoms in InAs host. We find the preference of the dimer ferromagnetic configuration of Mn dopants and an importance of optimizing the atomic site positions. The frequency-dependent optical and magneto-optical properties, namely the dielectric tensor (on-and off-diagonal components), the electron energy loss spectra, and the transversal Kerr effect (TKE), are calculated. Calculated TKE resonance in In1-xMnxAs (x=0.0625) is found to be in good agreement with corresponding experimental magneto-optical spectra. The origin of the large TKE is discussed.
We present recent experimental results on the structural, electrical, magnetic, and magneto-optic... more We present recent experimental results on the structural, electrical, magnetic, and magneto-optical properties of Mn-implanted Si and Co-doped TiO(2-delta) magnetic oxides. Si wafers, both n- and p-type, with high and low resistivity, were used as the starting materials for implantation with Mn ions at the fluencies up to 5 x 10(16) cm(-2). The saturation magnetization was found to show the lack of any regular dependence on the Si conductivity type, type of impurity and the short post-implantation annealing. According to XMCD Mn impurity in Si does not bear any appreciable magnetic moment at room temperature. The obtained results indicate that above room temperature ferromagnetism in Mn-implanted Si originates not from Mn impurity but rather from structural defects in Si. The TiO(2-delta):Co thin films were deposited on LaAlO3 (001) substrates by magnetron sputtering in the argon-oxygen atmosphere at oxygen partial pressure of 2 x 10(-6)-2 x 10(-4) Torr. The obtained transverse Kerr effect spectra at the visible and XMCD spectra indicate on intrinsic room temperature ferromagnetism in TiO(2-delta):Co thin films at low (&lt; 1%) volume fraction of Co.
We report optical and magneto-optical results as well as atomic force microscopy (AFM) and magnet... more We report optical and magneto-optical results as well as atomic force microscopy (AFM) and magnetic force microscopy (MFM) results for InFeSb samples prepared by laser ablation. AFM and MFM studies have revealed the presence of magnetic particles on the samples surface, whose sizes depend on the Fe content and substrate temperature. It has found that both optical and magneto-optical spectra are superposition of spectra from the doped InFeSb layers and particles on their surface.
Spectral and field dependencies of Transversal Kerr Effect (TKE) for [(Co45Fe45Zr10)Z(Al2O3)100-Z... more Spectral and field dependencies of Transversal Kerr Effect (TKE) for [(Co45Fe45Zr10)Z(Al2O3)100-Z(X)/α-Si:H(Y)] n multilayers have been studied in the energy range 0.5 - 4.0 eV. It was found that TKE field dependencies in the nearest IR energy range exhibit anomalous behavior for structures only with thin Si layers and this behavior vanishes with increasing of the Si layer thickness. TKE spectra measured in small and large magnetic fields were essentially different. It was shown that magneto-optical response of multilayered structure composite-silicon is the sum of contributions from two composites: (Co45Fe45Zr10) - Al2O3 + Si + silicides and (Co45Fe45Zr10) - Si + silicides, which have a different sign of TKE in the nearest IR spectrum and their magnetic states depend both on composite and semiconducting layer thicknesses.
INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005., 2005
The present study addresses the magneto-optical properties of CoX(TiO2)1-X and CoX(Sm2O3)X thin f... more The present study addresses the magneto-optical properties of CoX(TiO2)1-X and CoX(Sm2O3)X thin films in as-deposited state and after annealing. The films are composed of the granular ferromagnet-insulator composites where the nanometer-sized Co are embedded in either TiO2 or Sm2O3 insulating matrix. The magnetic properties of the films were measured by vibrating sample magnetometer (VSM) in magnetic field up to 20
We report magneto-optical spectra of the Heusler bulk alloys Ni-Mn-In, thin films Ni-Mn-Ga, micro... more We report magneto-optical spectra of the Heusler bulk alloys Ni-Mn-In, thin films Ni-Mn-Ga, microwires Ni-Mn-In and Ni-Mn-Ga in martensitic and austenitic states. Transversal Kerr effect (TKE) was studied at an angle of light incidence of 68° with respect to the sample plane, in the energy range 0.5 eV < E < 4.0 eV, at 50 350 K temperatures, and in magnetic fields up to 3.5 kOe. The TKE spectra profile does not change too much at martensitic transformation in Ni2MnGa thin films, only magnitudes of characteristic maxima decrease. The magneto-optical response of Ni2MnGa microwires is very similar to that for Ni2MnGa thin films. For most of studied bulk samples, the TKE signal is very weak (about 10-5), about two orders of magnitude smaller than for thin films, and in many cases could not be detected at all. It indicates the strong dependence of the magneto-optical response of Heusler alloys on the quality of optically or electrochemically polished surfaces and their microstructure.
We demonstrate that the colossal magnetoresistance (CMR) manganites doped with the monovalent cat... more We demonstrate that the colossal magnetoresistance (CMR) manganites doped with the monovalent cations of the large ionic radius A (A=Na+, K+, Ag+) reveal enhanced sensitivity of the electrical resistance to the magnetic field near the room temperature. The main obstacle to their practical application is severe difficulty of the synthesis, in particular, that of the thin films because of the high volatility or low thermal stability of the oxides of these doping elements. But the preparation of the films in two steps allows for the materials with the superior CMR characteristics. At the first step, epitaxial single phase precursor La1−xAyMnO3 (0.3≥x>y) is formed on the single crystal substrate due to the epitaxial stabilization by the single source MOCVD (metalorganic chemical vapor deposition) using thd-complexes. The second step is the isopiestic annealing with the powder mixture determining the high concentration of the volatile oxide in the gas phase resulting in the saturation of La1−xAxMnO3 (x=y) films by the gas phase transport. The film transformations are studied with XRD and HREM. The high magnetoresistance MR and magnetotransmission MT with the linear magnetic field (H) dependence near the room temperature (dMR/dH up to 45%/T, dMT/dH up to 15%/T) are reported.
Combined studies of the impedance and magneto-optical properties of porous silicon-cobalt nanocom... more Combined studies of the impedance and magneto-optical properties of porous silicon-cobalt nanocomposites are carried out. Correlations between the charge transfer over a nanocomposite layer and the spectral response of the transverse Kerr effect are revealed.
Spectral dependences of the transversal Kerr effect (TKE) as well as of the real and imaginary pa... more Spectral dependences of the transversal Kerr effect (TKE) as well as of the real and imaginary parts of the permittivity of InMnAs layers were studied. Pulsed laser ablation of Mn and InAs targets was used to form the layers on GaAs(100) substrates. Spectra of the optical constants and TKE depended substantially on layer fabrication conditions and testified to the presence of MnAs inclusions in the samples. The cross-sectional transmission electron microscopy revealed the presence of inclusions of size 10-40 nm in the layers. At room temperature a strong resonant band was observed in the TKE spectra of the InMnAs layers in the energy range of 0.5-2.2 eV. In this band the TKE was comparable in magnitude but opposite in sign to that in the strong ferromagnetic MnAs. The resonant character of the TKE spectra was explained by excitation of surface plasmons in the MnAs nanoclusters embedded in the InMnAs semiconductor host. Modelling the TKE spectra for (InAs)(1 - X):(MnAs)(X) nanocomposites in the effective-medium approximation (Maxwell-Garnett approximation) confirmed the assumption on the plasmon mechanism of the resonant enhancement of the transversal Kerr effect in the InMnAs layers.
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Papers by E. Gan'Shina