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[Ge.sub.1-x][Mn.sub.x]/Ge single-crystal heterojunction diodes with p-type [Ge.sub.1-x][Mn.sub.x] ferromagnetic semiconductor are grown on Ge substrates of p-type, n-type and intrinsic semiconductors by using molecular beam epitaxy. The I-V curve of the p-[Ge.sub.0.95][Mn.sub.0.05]/intrinsic-Ge diode is tuned by a magnetic field, which is shown by a large positive magnetoresistance.

Abstract: A series of FeCoB–SiO2 granular films were deposited on Kapton flexible substrates by magnetron co-sputtering technique at room temperature. All films are amorphous with granular morphology. The coercivity in the easy axis (Hce ) and the resistivity (ρ) decrease with the decrease of the Ar pressure, but they decrease with the increase of the film thickness. The granular films deposited at low Ar pressure exhibit obvious in-plane uniaxial magnetic anisotropy. Excellent soft magnetic properties with the Hce as low as 1.57Oe was obtained in the 500nm films deposited at 0.3Pa. In addition, high ρ (∼3.5mΩcm), relatively high complex permeability (μ′=152.8 at low frequency and ) and ferromagnetic resonance frequency (fr ∼3.61GHz) were simultaneously obtained. [Copyright &y& Elsevier]

Abstract: A series of FeCoB–SiO2/SiO2 multilayered granular films with various thickness were prepared by alternating co-sputtering FeCoB and SiO2 targets and single-sputtering SiO2 target. As-deposited films were annealed in a magnetic field at different temperature. The high-frequency magnetic and electrical transport properties were investigated. The films annealed above 250°C show good soft magnetic properties and obvious uniaxial magnetic anisotropy. The resistivity (ρ), coercivity (H ce) decrease and complex permeability (), ferromagnetic resonance frequency (f r ) increase with increasing annealing temperature and thickness. The desirable high ρ (∼5.92mΩcm), considerable frequency linewidth (Δf∼4.02GHz) and high (μ′=120 at low frequency, ) were obtained for the 252nm films annealed at 250°C. The amorphous or nanograin phase and strong exchange coupling effect are responsible for the good high-frequency magnetic performance. The electrical transport properties show the films with high ρ and large are near the conductive percolation threshold. Moreover, the Δf, damp coefficient (α) and Gilbert damping parameter (G) were discussed based on phenomenological Landau–Lifshitz–Gilbert equation. [Copyright &y& Elsevier]

The influence of exchange–coupling interaction on the effective anisotropy in nanocrystalline Nd2Fe14B permanent material has been investigated. The results show that the exchange–coupling interaction between grains causes a decrease of the effective anisotropy constant, Keff, with decreasing grain size. The variation of Keff with grain size is basically the same as that of coercivity. The decrease of the effective anisotropy is the main reason for the reduction of the coercivity. In order to get high anisotropy or coercivity in nanocrystalline Nd2Fe14B material, the grain size should be larger than 20 nm. [Copyright &y& Elsevier]

Abstract: The Zn0.32Co0.68O1− v /Pb hybrid junctions were prepared, where the concentrated magnetic semiconductor Zn0.32Co0.68O1− v is in the region of variable range hopping transport instead of the ballistic or diffusive transport. The high differential conductance peak at gap voltage and two above-gap peaks were observed below the superconducting critical temperature. Moreover, both the zero bias conductance peak and the finite bias conductance peak were observed below the gap voltage. All these differential conductance peaks systematically evolve and finally disappear as the temperature or the magnetic field increases. These transport phenomena were explained by phase coherent Andreev reflection in the presence of strong disorder, magnetic impurity scattering, and spin polarization. [Copyright &y& Elsevier]

Highlights: [•] Epitaxial anatase Fe0.05Ti0.95O2−δ thin films were grown on LaAlO3 substrates by pulsed laser deposition under different oxygen atmosphere. [•] The influence of oxygen vacancy on the magnetic, optical, and transport properties of Fe:TiO2 ferromagnetic semiconductor films has been investigated systematically. [•] The origin of the ferromagnetism was interpreted by a modified bounded magnetic polaron model. [Copyright &y& Elsevier]

Abstract: Co2+-doped ZnGa2O4 nanocrystals were prepared via a citrate sol–gel method. The as-obtained ZnGa2O4 nanocrystals are the only crystalline phase with an average diameter of 15–30nm in the temperature range of 500–700°C. Ga2O3 was detected when the powder was heated over 800°C. So we think that the suitable fired temperature for the preparation of ZnGa2O4 nanocrystals is 500–700°C. The observed absorption and emission spectra of the nanocrystalline powders in the visible and near infrared regions are characteristic of tetrahedral Co2+ ions. The crystal field parameter D q of 402cm−1 and the Racah parameters B of 765cm−1 and C of 3420cm−1 were estimated for tetrahedral Co2+ ions in ZnGa2O4 nanocrystals. [Copyright &y& Elsevier]