Papers by Keyword: GaMnAs

Abstract: The co-doping effect of Be and Mn have been studied in the ferromagnetic semiconductor (Ga,Mn)As thin films. The measurement of magnetic properties shows that the Be doping decreases the Curie temperatures of the ferromagnetic sample due to defects formation. The transport studies show that the Be incorporation decreases the resistivity of the (Ga,Mn)As thin films. It is found that Be incorporation decreases the planar Hall resistance but increases the resistance transitions in the magnetic samples.

Abstract: The co-doping effect of Si and Mn have been studied in the low temperature grown ferromagnetic semiconductor (Ga,Mn)As thin films. It is found that Si doping decreases the Curie temperatures of the ferromagnetic sample due to carrier compensation and defects formation. The transport studies show that the Si incorporation increases the resistivity of the (Ga,Mn)As thin films, and increase the planar Hall resistance while increases the resistance transitions in the magnetic samples.

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.

Abstract: The new hybrid device consisting of patterned array of Co nanodots on GaMnAs channel was fabricated and demonstrated to give a new functionality to control the transport properties of GaMnAs. Magnetic state of array of Co nanodots was observed with magnetic force microscopy (MFM) observation. The magnetic state of individual Co dots can be controlled by using a MFM tip. Different distribution of magnetic state of Co nanodots in an array structure resulted in an inhomogeneous magnetic field. Magnetic field induced by the array of nanodots leads to change in the transport properties of GaMnAs. This inhomogeneous magnetic field was regarded to act as an effective potential that can trap the spin polarized carriers in the GaMnAs system with giant Zeeman splitting.

Abstract: Anisotropy magneto-resistance and planar Hall-effect of ferromagnetic GaMnAs epitaxial films were investigated. The films were grown on 2 o off-cut GaAs (001) substrate in an optimized growth condition via low temperature molecular beam epitaxy. The GaMnAs layer revealed an easy axis along the (2x4) reconstruction direction of the substrate or along the off-cut direction. The large value of the anisotropy magneto-resistance ratio of ~7 % was realized by a well-alignment of the easy axis of the homogeneous ferromagnetic GaMnAs layer with the current. It also gives a very high planar Hall resistance ratio of ~500 %.