Papers by Author: O.V. Vikhrova

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: t is reported about fabrication by laser deposition in a gaseous environment of epitaxial layers of ferromagnetic semiconductors GaMnSb and InMnSb. Investigations of x-ray diffraction and Raman scattering showed reasonably good crystal quality of GaMnSb and InMnSb layers. Magnetic properties were investigated by magneto-optical transversal Kerr effect and Hall effect. It is established, that GaMnSb layers are ferromagnetic at room temperature. In contrast, InMnSb samples demonstrate the ferromagnetic properties only at low temperatures (< 70 K).

Abstract: Optical and magneto-optical properties of GaMnSb layers fabricated on GaAs (001) substrates by laser ablation technique were studied using spectral ellipsometry (E =1.24-3.25 eV) and the transversal Kerr effect (TKE) (E = 0.5 4.2 eV) as well as atomic and magnetic force microscopy. Spectra of the constituents of the diagonal components of the permittivity tensor as well as TKE depended substantially on the layer fabrication conditions. At room temperature a strong resonant band was observed in the TKE spectra for the GaMnSb layers with low Mn content in the energy range E 0.5-1.5 eV. This resonant TKE band was explained by excitation of surface plasmons in MnSb nanoclusters, which arose during the growth of the layers. In the energy region E >1.5 eV the TKE spectra were related to interband transitions in MnSb inclusions.

Abstract: Laser deposition method was used for growing ferromagnetic semiconductor and half-metal compound layers. GaMnAs and InMnAs layers were grown by alternating laser ablation of solid targets (semiconductor and Mn) in hydrogen and arsine flow. The layers exhibited ferromagnetic properties (detected by Hall effect measurements) from 10 K to room temperature (for InMnAs). Half-metal compound layers were deposited by the techniques of reactive laser deposition (MnAs, MnP) and alternating laser deposition (MnSb). The half-metal layers exhibit ferromagnetism at temperatures up to 300 K.

Abstract: Optical and magneto-optical properties of In(Ga)MnAs layers fabricated by laser ablation on GaAs(100) substrates were studied. Spectra of the optical constants and the transversal Kerr effect (TKE) depended substantially on the conditions of layer fabrication and testified to the presence of MnAs inclusions in all the samples. The cross-sectional transmission electron microscopy revealed the presence in the layers of inclusions 10-40 nm in size. At room temperature, a strong resonant band was observed in the TKE spectra of some In(Ga)MnAs layers in the energy range 0.5-2.7 eV. The resonant character of the TKE spectra was explained by excitation of surface plasmons in the MnAs nanoclusters embedded in the semiconductor host.