DD
D.G. De Groot
9 records found
1
At low fluences, the [Sr]/[Ti] ratio of laser deposited SrTiO3 films appears to be a function of the laser fluence. The deviation from stoichiometry is remarkably constant in time. From an analysis of both the composition of the film and the irradiated target, we deduce a volume-
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Investigating the epitaxial nature of YBa2Cu3O7-δ films on NdGaO3 (001) by Rutherford backscattering (RBS) and X-ray diffraction (XRD) texture measurements we find that the films are almost single crystalline, in the sense that the a, b and c axes are uniquely defined with respec
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YBa2Cu3O7-δ films on SrTiO3 are characterized by a network of anti-phase boundaries (APB's), protruding from the interface to the film surface. We propose that the island morphology of these films is to a large extent determined by this
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High quality twin-free c-axis oriented YBa2Cu3O7-δ films were grown by pulsed laser deposition on NdGaO3. We find resistive anisotropies between 1 < ρa/ ρb < 1.6. The resistive anisotropy above Tc appears to be correlated to the anisotropy in the critical current below Tc. The no
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We report on the magnetic and transport properties of thin films of La0.67Ca0.33MnO3 as a function of annealing temperature, substrate material and film thickness. The films were sputtered from a stoichiometric target with the same nominal composition and were grown epitaxially o
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We provide evidence that non-stoichiometric ablation of YBa2Cu3O7-δ at low fluences is due to a phase separation of the target surface. On the other hand, in SrTiO3 we find at low fluences evidence for preferential ablation which is ass
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Projection optics is a means to reduce the spatial energy density variations on the target during laser ablation. Using projection optics to study the interaction between a spatially uniform 248 nm excimer laser beam and a YBa2Cu3O6+x target we observe a well-defined threshold fl
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Using projection optics we made a detailed study of the interaction of a spatially uniform 248 nm excimer laser beam and a 99% dense YBa 2Cu3O6+x target. Below a threshold fluence of 1 J/cm2 the roughness of the irradiated target increases dramatically due to non-stoichiometric a
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The dynamical relaxation rate Q dln js/dln(dB/dt) where js is the current induced in a superconductor when the external field is swept at a rate dB/dt, has been measured in YBa2Cu3O7 and Y2Ba4Cu8O16 films of 100 nm and 180 nm thickness as a function of magnetic field at temperatu
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