Search results for "conductivity"
showing 10 items of 1988 documents
Quadratic nonlinear optical parameters of 7% MgO-doped LiNbO3 crystal
2016
International audience; Pure and 7% MgO-doped lithium niobate (LiNbO3) single crystals were grown by the Czochralski technique. The shift of optical absorption edge in 7% MgO-doped crystal in direction of shorter wavelength compared to undoped crystal was observed. The second harmonic generation measurements of 7% MgO-doped LiNbO3 crystal were performed at room temperature by means of the rotational Maker fringe technique using Nd:YAG laser generating at 1064 nm in picoseconds regime. Experimentally obtained value of nonlinear optical coefficient d33 for 7% MgO-doped LiNbO3 was found to be less than for undoped crystal but higher than for 5% MgO-doped. I-type phase-matched second harmonic g…
Luminescence and vacuum ultraviolet excitation spectroscopy of cerium doped Gd3Ga3Al2O12 single crystalline scintillators under synchrotron radiation…
2020
Authors gratefully acknowledge the financial support from the Latvian Science Council grant LZP-2018/2-0358 . The research leading to this result has been supported by the project CALIPSO plus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON2020 . The work of A.P.K. was supported by the Ministry of Science and Higher Education of the Russian Federation , state contracts No. 11.6181.2017/ITR .
Metallophthalocyanines as optical active dopants in borate glass
2021
Abstract B2O3 – phthalocyanine composites (B2O3@MPc) were synthesized at 410 °C by sintering boron trioxide doped with base metal-free phthalocyanine (H2Pc) and/or its complexes of Mg, Zn, Gd (Pc = C32H16N8, phthalocyanine ligand, M = metal ion). The glassy products were characterized by scanning electron microscopy (SEM, EDS) and diffuse reflectance spectroscopy (DRS) which confirmed the incorporation of the respective phthalocyanines into the amorphous borate matrix. FTIR results suggested a possible impact of the phthalocyanine dopants on the final solid structure of the glassy matrix. The UV-excited composites emitted a pronounced blue phosphorescence featured by a two-step quenching pr…
Formation and Rupture of Schottky Nanocontacts on ZnO Nanocolumns
2007
In this paper, the electrical transport and mechanical properties of Pt/ZnO Schottky nanocontacts have been studied simultaneously during the formation and rupture of the nanocontacts. By combining multidimensional conducting scanning force spectroscopy with appropriated data processing, the physical relevant parameters (the ideality factor, the Schottky barrier height, and the rupture voltage) are obtained. It has been found that the transport curves strongly depend on the loading force. For loading forces higher than a threshold value, the transport characteristics are similar to those of large-area Schottky contact, while below this threshold deviations from strictly thermionic emission …
Domain wall induced modulation of low field H-T phase diagram in patterned superconductor-ferromagnet stripes
2019
We present a systematic study of the magnetic domain wall induced modulation of superconducting transition temperature (Tc) in Nb/Ni bilayer stripes. By varying the thickness of the Ni layer from 20 nm to 100 nm we have been able to measure the low field Tc-H phase diagram spanning the Neel domain wall and Bloch domain wall range of thicknesses. Micromagnetic simulations and magnetic force microscopy measurements confirmed a stronger out-of-plane stray field in the Bloch domain walls compared to the Neel walls. A suppression in Tc was observed in the magnetization reversal region of the Ni film, the magnitude of which followed linearly to the strength of the out-of-plane stray field due to …
Magnetotransport properties of epitaxial - and -oriented CeSb thin films
2000
Abstract We present the electronic magnetotransport properties of (1 0 0) - and (1 1 1) -oriented CeSb thin films. The samples were grown epitaxially by molecular beam epitaxy onto sapphire (1 1 2 0) and (0 0 0 1) substrates. The temperature-dependent resistivity is in full correspondence with the behaviour known from bulk material. For (1 0 0) -oriented films the analysis of the temperature and magnetic field-dependent magnetoresistivity results in a H/T phase diagram analogous to that of bulk samples. For (1 1 1) -oriented films slight deviations were observed. In Hall-effect measurements of (1 0 0) -oriented samples a sign change of the Hall coefficient occurred which is in contrast to m…
Magnetism of Co-doped ZnO thin films
2007
We have investigated magnetic and transport properties of 5% Co-doped and undoped ZnO thin films deposited on $r$ plane ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ substrates by pulsed laser deposition. The Co doped films showed paramagnetic and ferromagnetic behavior as well as a high magnetoresistance and a small anomalous Hall effect. In a range of $0\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}5\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ at low temperatures we observed a double sign change of the magnetoresistance. For undoped ZnO films, prepared by the same conditions, only a negative MR was observed, but surprisingly also a very small anomalous Hall effect. We explain our results…
Spin polarization of magnetoresistive materials by point contact spectroscopy
2003
In the strive to find a straightforward method for determining the spin polarization, the analysis of the Andreev reflection process in point contact junctions has attracted much interest. However, the prerequisite for anevaluation of the transport spin polarization in this scheme is the existence of elastic (ballistic or diffusive) transport, which cannot be assumed a priori. We therefore also include inelastic processes in our analysis and exemplify that thermal effects can have a significant effect on data evaluation. As ferromagnetic samples with a predicted half metallic behavior and comparably low conductivity we used thin films of the double perovskite Sr 2 FeMoO 6 and bulk material …
Impact of granularity on transport properties of mechanically stressed La0.67Ca0.33MnO3 films
2001
Abstract (La,Ca)MnO 3 is one of so called collosal magnetoresistive materials and it is of interest to correlate its transport properties to film growth in order to optimize its performance. Two-hundred nanometers thick (100)La 0.67 Ca 0.33 MnO 3 films were grown by laser ablation on (100)SrTiO 3 , (100)LaAlO 3 and (100)(LaAlO 3 ) 0.3 +(Sr 2 AlTaO 6 ) 0.7 substrates. The films were granular in structure with low angle boundaries between the grains. The volume of the unit cell was considerably smaller for films grown on a SrTiO 3 substrate than on LaAlO 3 . At temperatures higher than the one where the spins order, the strongest response of resistivity on temperature ρ ( T ) was measured for…
Hydrodynamical aspects of the floating zone silicon crystal growth process
2014
Abstract 3D numerical modeling of dopant transport in the melt is carried out for the 100 mm floating zone silicon single crystal growth process. The axis-symmetric shape of the molten zone is calculated with the program FZone considering the coil and the high frequency (HF) electromagnetic (EM) field in 3D. Time dependent melt flow, temperature and dopant concentration fields are modeled using a specialized solver based on the open source code library OpenFOAM ® . The influence of the Marangoni coefficient in the boundary conditions on the melt velocity field is analyzed. The obtained shapes of the crystallization interface and resistivity profiles in the grown crystal are compared with ex…