Papers by Keyword: Diluted Magnetic Semiconductor (DMS)

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Authors: E.T. Kulatov, A. Titov, Y.A. Uspenskii
Abstract: 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 InSb (As) hosts. 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 reflectivity, the electron energy loss spectra, on-and off-diagonal conductivity tensor and the polar Kerr effect, are calculated for comparison with available experimental data. Our calculated MO resonance in In1-xMnxSb (x=1.56%) are found to be in good agreement with corresponding experimental MO spectra. The origin of the large Kerr rotation is discussed.
Authors: X. Gratens, Samih Isber, S. Charar, Z. Golacki
Abstract: The magnetic susceptibility of Pb1-xCexX (X = S, Se and Te) crystals with several Cerium concentrations ranging from x = 0.006 to 0.036 has been measured between 2 K and 300 K. The experimental susceptibility curves were found to be consistent with a 2F5/2 lowest manifold for Ce3+ ions; the cubic crystal-field splitting values of 2F5/2 were estimated to be about 340 K, 440 K and 540 K for Pb1-xCexTe, Pb1-xCexSe, and Pb1-xCexS, respectively. For all the studied samples, it was found that the 7 doublet lies below the 8 quadruplet. These results confirm that Ce3+ ions substitute Pb2+ in the host crystals. Furthermore, the effective Landé factors were determined by X-band (~9.5 GHz) Electron Paramagnetic Measurements (EPR) to be g = 1.333, 1.364, and 1.402 for Ce ions in PbX, X = S, Se, and Te, respectively.
Authors: C. Benoit à la Guillaume
Authors: Pushan Banerjee, B. Ghosh
Abstract: The present paper describes the contacting technology to the diluted magnetic semiconductor Cd1-xMnxTe having potential applications in optoelectronic and spintronic devices. For efficient spin injection into a spintronic material, a matching ohmic contact is the demand of the time. Since cadmium telluride has a well-known contact problem, its manganese-doped counterpart is also facing a similar difficulty. In the present case Cd1-xMnxTe was fabricated using thermally assisted interdiffusion and compound formation between repeated stacked elemental layers of manganese, cadmium and tellurium. A wet electroless deposition technique was employed to deposit manganese doped nickel phosphide as a magnetic contact onto Cd1-xMnxTe. It appeared that the contact resistivity improved compared to the case of gold contact. The details of the contacting technology and the results have been described in the text of the paper.
Authors: R.A.J.R. Sheeba, R. Saravanan, L. John Berchmans
Abstract: An effort has been made to understand the charge density distribution of the Si and Ge based diluted magnetic semiconductors. A theoretical analysis has been done on the variation of charge densities when the semiconductors Si and Ge are doped with the transition metal atoms of V, Mn and Co with different concentrations of x (0.02, 0.04, 0.06, 0.08, and 0.10), in Si1-xMx and Ge1-xMx. Two dimensional electron density contour maps have been plotted for all the compositions studied in this work. The theoretical mid bond densities were found out for the compounds which can be taken as the reference values for comparison of the experimental values of the same compositions.
Authors: Yoon Suk Kim, Hwan Kim, B.D. Yu, Duck Kyun Choi, Yong Chae Chung
Authors: R.K. Singhal, M.S. Dhawan, S.K. Gaur, Elisa Saitovitch
Abstract: ZnO semiconductor doped with a few per cent of some transition metal ions can exhibit above room temperature ferromagnetism, transforming it into a very promising candidate for future spin-electronic applications. In the present article we have compared the electronic structure of two polycrystalline ZnMnO pellets doped with diluted Mn concentration (2% and 4%), carefully characterized by SQUID and XRD, including Rietveld refinement. The characterization measurements established that the samples have the ZnO lattice with ZnS type Wurtzite hexagonal symmetry and no detectable impurities. The samples exhibit distinctly different magnetic properties. The 2% sample displayed a clear FM ordering at 300 K while the 4% sample did not show any ordering down to 5K. The electronic structure of these two samples has been investigated using Mn L23 x-ray absorption spectroscopy, Zn 2p and 3p, Mn 3p and O 1s x-ray photoemission spectroscopy. Our aim was to find out how the changes in the electronic structure can correlate to the observed magnetic properties in such diluted magnetic semiconductor materials. The results show that most of the Mn ions of the ferromagnetic sample are in the divalent state. For the higher Mn percent nonmagnetic sample, a larger contribution of higher oxidation Mn states are dominant and the oxygen content also increases. The two factors can be correlated to the suppressed ferromagnetism, though it is hard to pinpoint that which of these two weighs more in the suppression mechanism.
Authors: V. Bindilatti, N.F. Oliveira Jr., E. ter Haar, Y. Shapira
Authors: V.A. Kulbachinskii, L. Shchurova
Abstract: We have investigated the thermodynamic, transport and magnetotransport properties of free charge carriers in a diluted magnetic semiconductor with a quantum well InGaAs in the GaAs with δ-doped by C and Mn. In order to determine the density of the holes in a quantum well, we carried out thermodynamic calculations of the system of free holes, atoms Mn0 and ions Mn–. We calculated the temperature dependence of resistance and magnetoresistance of holes in the quantum well. The contributions of various scattering mechanisms of holes to the resistance were analyzed. The negative magnetoresistance are explained as the reduction of spin-flip scattering by aligning spins of the magnetic field.
Authors: Yu Liang Zhang, Xiao Feng Li
Abstract: The structure and the magnetic properties of 3.0 and 0.3 at.% Mn-containing ZnO-based DMSs, synthesized by a straightforward and experimentally simple nonaqueous route, have been investigated by various characterization techniques, including XRD, HRTEM, and EPR. The as-synthesized doped ZnO nanocrystals retain the wurtzite structure with a morphology in the form of flower-like shape. EPR spectra with g-factor values of 2.0023(3% at.%) and 2.0019(0.3 at.%), respectively, at room temperature were obtained, confirming that the Mn2+ is substitutionally incorporated into the ZnO nanocrystals.
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