Magnetoresistance in Sn-Doped In2O3Nanowires

In this work, we present transport measurements of individual Sn-doped In2O3nanowires as a function of temperature and magnetic field. The results showed a localized character of the resistivity at low temperatures as evidenced by the presence of a negative temperature coefficient resistance in temperatures lower than 77 K. The weak localization was pointed as the mechanism responsible by the negative temperature coefficient of the resistance at low temperatures

Electrical properties of diamond films prepared from carbon disulfide and ethanol in hydrogen

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Sulfur doping of diamond samples produced by the hot-filament chemical vapor deposition (CVD) process using carbon disulfide highly diluted in ethanol and hydrogen has been investigated. The polycrystalline morphology observed by Scanning Electron Microscopy (SEM) and the characteristic diamond Raman peak were practically not affected by addition of CS(2) in the range of 0.8-2.0% by volume. The electrical resistivity dependence due to CS(2) addition showed a "down-and-up" curve with minimum resistivity of about 3.6 x 10(-4) Omega cm. Hall mobility as high as 325.9 cm(2)V(-1)s(-1) have been achieved. PIXE and XRF measurements showed that sulfur (100-400 ppm) was incorporated during the deposition independent of the CS(2) added. Unintentional contaminations with Si, W, Cu and Cr have been detected. All the samples, measured by hot-point method and Hall effect, showed p-type characteristics. (C) 2010 Elsevier Ltd. All rights reserved.852180183Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Magnetic and superconducting properties of RuSr2Gd1.5Ce0.5Cu2O10-delta samples: Dependence on the oxygen content and aging effects

The magnetic and superconducting properties of RuSr2Gd1.5Ce0.5Cu2O10-delta polycrystalline samples with different oxygen-doping levels are presented. A strong suppression of the superconducting temperature (T-c), as well as a reduction in the superconducting fraction, occurs as the oxygen content is reduced by annealing the samples in oxygen-deprived atmospheres. Drastic changes in the electrical resistivity are observed above T-c, possibly associated with oxygen removal, mainly from grain boundaries. However, the magnetic ordering is relatively less affected by the changes in oxygen content of the samples. The spin-glass transition is enhanced and shifted to higher temperatures with the reduction in oxygen content. This could be correlated with an increase in the spin disorder and frustration for the oxygen-depleted samples. Also, the same oxygen-vacancy-induced disorder could explain the reduction in the fraction of the sample showing antiferromagnetic order. We also report significant changes in the measured properties of the samples as a function of time.711