Pt-based metallization of PMOS devices for the fabrication of monolithic semiconducting/YBa2Cu3O7-d superconducting devices on silicon

Mo, Pt, Pt/Mo and Pt/Ti thin films have been deposited onto Si and SiO2 substrates by RF sputtering and annealed in the YBa2Cu3O7-d growth conditions. The effect of annealing on the sheet resitance of unpatterned layers was measured. A Pt-based multilayered metallization for the PMOS devices was proposed and tested for the monolithic integration of PMOS devices and YBCO sensors on the same silicon substrate. The best results were obtained with a Pt/Ti/Mo-silicide structure showing (0.472 \Omega_{\Box}) interconnect sheet resistivity and $2 \times 10^{-4} \Omega \cdot cm^{2}$ specific contact resistivity after annealing for (60) minutes at (700^{\circ})C in (0.5) mbar O(_{2}) pressure.Comment: 6 pages, accepted for Microelectronic Engineering, elsevie

Effect of ferroelectric layers on the magnetocapacitance properties of superlattices-based oxide multiferroics

A series of superlattices composed of ferromagnetic La$_{0.7}$Ca$_{0.3}$MnO$_3$ (LCMO) and ferroelectric/paraelectric Ba$_{1-x}$Sr$_x$TiO$_3$ (0$\leq$x$\leq$1) were deposited on SrTiO$_3$ substrates using the pulsed laser deposition. Films of epitaxial nature comprised of spherical mounds having uniform size are obtained. Magnetotransport properties of the films reveal a ferromagnetic Curie temperature in the range of 145-158 K and negative magnetoresistance as high as 30%, depending on the type of ferroelectric layers employed for their growth (\QTR{it}{i.e.} '\QTR{it}{x'} value). Ferroelectricity at temperatures ranging from 55 K to 105 K is also observed, depending on the barium content. More importantly, the multiferroic nature of the film is determined by the appearance of negative magnetocapacitance, which was found to be maximum around the ferroelectric transition temperature (3% per \QTR{it}{tesla}). These results are understood based on the role of the ferroelectric/paraelectric layers and strains in inducing the multiferroism.Comment: Accepted to Applied Physics Letter

YBCO Transition Edge Sensors Used For Very Low Noise Thermal Control

In electrically substituted radiometers, the ultra low noise control of the temperature is required. In this framework, we present results dedicated to the temperature regulation of copper plates, 3 cm diameter and 1 mm thick, using YBa2Cu3O7-d (YBCO) transition edge sensors (TES). One of the TES was used as the active thermometer of the temperature control unit, whereas the two others measured the plate temperature behavior. Two heating resistors were wound along a spiral pattern, just underneath the copper plate, to minimize the heating delay. The correlation between the two TES was clearly highlighted by applying a small heat perturbation through the second distributed resistor, the path of which closely follows that of the main resistor. Calibrated temperature oscillations of 30 microK rms at 10mHz together with spectral analysis were measured and a temperature resolution in the range of a few microK rms was achieved.Comment: 6 pages, ASC 2002 (Applied Superconductivity Conference), Houston, TX USA (Aout 2002): Oral contribution, to be published in IEEE Trans. Appl. Supercond. June 200

Correlation between structure and properties in multiferroic La0.7_{0.7}Ca0.3_{0.3}MnO3_3/BaTiO3_3 superlattices

Superlattices composed of ferromagnetics, namely La$_{0.7}$Ca$_{0.3}$MnO$_3$ (LCMO), and ferroelectrics, namely, BaTiO$_3$(BTO) were grown on SrTiO$_3$ at 720$^o$C by pulsed laser deposition process. While the out-of-plane lattice parameters of the superlattices, as extracted from the X-ray diffraction studies, were found to be dependent on the BTO layer thickness, the in-plane lattice parameter is almost constant. The evolution of the strains, their nature, and their distribution in the samples, were examined by the conventional sin$^2\psi$ method. The effects of structural variation on the physical properties, as well as the possible role of the strain on inducing the multiferroism in the superlattices, have also been discussed.Comment: To be published in Journal of Applied Physic

La manipulation des espèces animales. Réflexion anthropologique sur la qualification du sauvage

La réintroduction et le contrôle des populations réintroduites, de certaines espèces sauvages (l’ours, le lynx, le hamster commun, le castor par exemple) nécessitent la mise en place de protocoles biologique, juridique, économique, sociologique complexes. Ils demandent aussi la prise en compte de la représentation de ces espèces lorsque leur "retour" sur des territoires donnés se fait par l’intermédiaire de techniques de capture, de déplacement, d’élevage et de contrôle sophistiqués. Cet article explore les relations homme/animal dans une perspective anthropologique et s’interroge sur l’apparition d’un "sauvage réinventé". S’inscrivant dans le prolongement d’une réflexion sur l’ambiguïté catégorielle du sauvage et de son statut, la question des méthodes et les pratiques, développées en matière d’"élevage" d’espèces réintroduites, est posée ainsi que les problèmes sociétaux qui en découlent.The reintroduction and monitoring of reintroduced populations of some wildlife (bear, lynx, common hamsters, beavers, for example) require the establishment of complex protocols (biological, legal, economic, sociological). They also require taking into account the representation of these species when they "come back" through capture techniques, breeding and sophisticated control. This text explores the human / animal relationship from an anthropological perspective and examines the emergence of a "reinvented savage" that challenges the conventional classification systems. It enrolled in the Following reflection on the categorical ambiguity of wild and status. It questions, from field data, on one hand the methods and practices developed in terms of "breeding" of reintroduced species, on the other hand societal problems which arise

Resistive hystersis effects in perovskite oxide-based heterostructure junctions

In this paper, we report the electrical and structural properties of the oxide-based metal/ferroelectric/metal (MFM) junctions. The heterostructures are composed of ultrathin layers of La0.7Ca0.3MnO3 (LCMO) as a metallic layer and, BaTiO3 (BTO) as a ferroelectric layer. Junction based devices, having the dimensions of 400 x 200 micom2, have been fabricated upon LCMO/BTO/LCMO heterostructures by photolithography and Ar-ion milling technique. The DC current-voltage (I-V) characteristics of the MFM junctions were carried out. At 300 K, the devices showed the linear (I-V) characteristics, whereas at 77 K, (I-V) curves exhibited some reproducible switching behaviours with well-defined remnant currents. The resulting resistance modulation is very different from what was already reported in ultrathin ferroelectric layers displaying resistive switching. A model is presented to explain the datasComment: To be publised in Applied Physics Letter

Sizing of an Electric Power Steering system on dynamic and energetic criteria

International audienceThis paper presents the methodology to size a mechatronic system on dynamic and energetic criteria. The methodology is based on the establishment of the inverse model from the bond graph representation of the system by using the bicausality concept. By means of an automotive example, we illustrate the methodology and we present a solution to extend it to more complex problem

Nonresonant microwave absorption in epitaxial La-Sr-Mn-O films and its relation to colossal magnetoresistance

We study magnetic-field-dependent nonresonant microwave absorption and dispersion in thin La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ films and show that it originates from the colossal magnetoresistance. We develop the model for magnetoresistance of a thin ferromagnetic film in oblique magnetic field. The model accounts fairly well for our experimental findings, as well as for results of other researchers. We demonstrate that nonresonant microwave absorption is a powerful technique that allows contactless measurement of magnetic properties of thin films, including magnetoresistance, anisotropy field and coercive field.Comment: 20 pages, 11 figure