Multiple nodeless superconducting gaps in optimally-doped SrTi1−x_{1-x}Nbx_{x}O3_{3}

We present the first study of thermal conductivity in superconducting SrTi$_{1-x}$Nb$_{x}$O$_{3}$, sufficiently doped to be near its maximum critical temperature. The bulk critical temperature, determined by the jump in specific heat, occurs at a significantly lower temperature than the resistive T$_{c}$. Thermal conductivity, dominated by the electron contribution, deviates from its normal-state magnitude at bulk T$_{c}$, following a Bardeen-Rickayzen-Tewordt (BRT) behavior, expected for thermal transport by Bogoliubov excitations. Absence of a T-linear term at very low temperatures rules out the presence of nodal quasi-particles. On the other hand, the field dependence of thermal conductivity points to the existence of at least two distinct superconducting gaps. We conclude that optimally-doped strontium titanate is a multigap nodeless superconductor.Comment: 6 pages including a supplemen

La spectrometrie de masse d'ions secondaires: application a l'etude de l'interaction de H_2"1"8O avec TiO_2(100) et de depots metalliques supportes par des oxydes

SIGLEINIST T 73981 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Fragment kirjast tundmatule

Jomard, Edme Francois, 1777-1862, prantsuse insener, geograaf ja arheoloo

Cross-characterization methods to obtain an “absolute” quantification of Cu(In,Ga)Se 2 in-depth and at the surface

International audienc

Did the Younger Dryas to Holocene climate transition favour high seismicity rates in the north‐western Alps?

International audienceIn the French north-western Alps, several lakes of glacial origin, such as Aiguebelette and La Thuile, present some mass-transport deposits within their sedimentary sequences. These event layers can result from lake sediment destabilization eventually triggered by earthquakes. On Lake Aiguebelette, based on sedimentological, geochemical and magnetic analyses, and high-resolution seismic and bathymetric surveys a ca 1 m thick event layer was identified in the deepest lake basin and a synchronous ca 2 cm thick deposit in the shallow basin. Age-depth models based on radiocarbon ages reveal that both mass-transport deposits in Lake Aiguebelette occurred around the Younger Dryas - Early Holocene climatic transition (i.e. 11 700 cal bp) time range. In Lake La Thuile, located 30 km away, unique mass-transport deposits (translational slide type) were recorded at the same time range in sedimentary records. Additionally, high-resolution seismic profiles previously acquired in Lake Annecy and Lake Bourget support the hypothesis of significant mass-transport deposits occurring at the Younger Dryas - Early Holocene time range. These outcomes on four north-western peri-Alpine and Alpine lakes highlight the regional occurrence of mass-transport deposits in the Younger Dryas - Early Holocene time range. Seismic and rockfall events are discussed as potential sources of these significant and similarly aged mass-transport deposits. Based on this study and a literature review, the authors suggest that mechanisms induced by rapid climate change and glacial retreat, such as crustal rebound and erosional unloading, could favour the triggering of earthquakes and rockfall events. In the case of mass-transport deposits archived in north-western Alpine lakes during this time period, this study favours the hypothesis of increased seismicity as the primary source driving process involved

The effect of microstructure and film composition on the mechanical properties of linear antenna CVD diamond thin films

Abstract: This study reports the impact of film microstructure and composition on the Young's modulus and residual stress in nanocrystalline diamond (NCD) thin films (approximate to 250 nm thick) grown on silicon substrates using a linear antenna microwave plasma-enhanced chemical vapor deposition (CVD) system. Combining laser acoustic wave spectroscopy to determine the elastic properties with simple wafer curvature measurements, a straightforward method to determine the intrinsic stress in NCD films is presented. Two deposition parameters are varied: (1) the substrate temperature from 400 degrees C to 900 degrees C, and (2) the [P]/[C] ratio from 0 ppm to 8090 ppm in the H2/CH4/CO2/PH3 diamond CVD plasma. The introduction of PH3 induces a transition in the morphology of the diamond film, shifting from NCD with larger grains to ultra-NCD with a smaller grain size, concurrently resulting in a decrease in Young's modulus. Results show that the highest Young's modulus of (1130 +/- 50) GPa for the undoped NCD deposited at 800 degrees C is comparable to single crystal diamond, indicating that NCD with excellent mechanical properties is achievable with our process for thin diamond films. Based on the film stress results, we propose the origins of tensile intrinsic stress in the diamond films. In NCD, the tensile intrinsic stress is attributed to larger grain size, while in ultra-NCD films the tensile intrinsic stress is due to grain boundaries and impurities