Ukinite vrijeme, sklonite satove

Satovi su prisutni u svim aspektima života jer najavljuju glavne događaje dana. Kako bi izazvao vrijeme koje nam govori što trebamo činiti, tim francuskog vrtića odlučio je da će poskidati sve satove i pustiti inspiraciji da ih vodi iz dana u dan

Le monde du tout petit, petit, petit, petit...

La concordance d’un certain nombre d’évolutions techniques et la rencontre des physiciens avec des chimistes et des biologistes ont permis la fabrication et l’observation d’objets de plus en plus petits pour se diriger vers l’infiniment petit. Exploration avec Alain Schuhl

High domain wall velocities induced by current in ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy

Current-induced domain wall (DW) displacements in an array of ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy have been directly observed by wide field Kerr microscopy. DWs in all wires in the array were driven simultaneously and their displacement on the micrometer-scale was controlled by the current pulse amplitude and duration. At the lower current densities where DW displacements were observed (j less than or equal to 1.5 x 10^12 A/m^2), the DW motion obeys a creep law. At higher current density (j = 1.8 x 10^12 A/m^2), zero-field average DW velocities up to 130 +/- 10 m/s were recorded.Comment: Minor changes to Fig. 1(b) and text, correcting for the fact that domain walls were subsequently found to move counter to the electron flow. References update

Chiral damping of magnetic domain walls

Structural symmetry breaking in magnetic materials is responsible for a variety of outstanding physical phenomena. Examples range from the existence of multiferroics, to current induced spin orbit torques (SOT) and the formation of topological magnetic structures. In this letter we bring into light a novel effect of the structural inversion asymmetry (SIA): a chiral damping mechanism. This phenomenon is evidenced by measuring the field driven domain wall (DW) motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The difficulty in evidencing the chiral damping is that the ensuing DW dynamics exhibit identical spatial symmetry to those expected from the Dzyaloshinskii-Moriya interaction (DMI). Despite this fundamental resemblance, the two scenarios are differentiated by their time reversal properties: while DMI is a conservative effect that can be modeled by an effective field, the chiral damping is purely dissipative and has no influence on the equilibrium magnetic texture. When the DW motion is modulated by an in-plane magnetic field, it reveals the structure of the internal fields experienced by the DWs, allowing to distinguish the physical mechanism. The observation of the chiral damping, not only enriches the spectrum of physical phenomena engendered by the SIA, but since it can coexists with DMI it is essential for conceiving DW and skyrmion devices

The domain wall spin torque-meter

We report the direct measurement of the non-adiabatic component of the spin-torque in domain walls. Our method is independent of both the pinning of the domain wall in the wire as well as of the Gilbert damping parameter. We demonstrate that the ratio between the non-adiabatic and the adiabatic components can be as high as 1, and explain this high value by the importance of the spin-flip rate to the non-adiabatic torque. Besides their fundamental significance these results open the way for applications by demonstrating a significant increase of the spin torque efficiency.Comment: 12 pages plus supplementary note

Numérique et libertés : un nouvel âge démocratique

Installée en juin 2014 par le Président de l\u27Assemblée nationale, la commission de réflexion sur le droit et les libertés à l\u27âge du numérique présente 100 propositions concernant les enjeux liés au numérique : instauration d\u27un droit de savoir par la mise à disposition de tous des informations d\u27intérêt public ; renforcement de la protection des lanceurs d\u27alerte ; défense de la liberté d\u27expression à l\u27ère du numérique en préservant la loi de 1881 sur la liberté de la presse et la place du juge garant de cette liberté ; renforcement de la protection des droits fondamentaux face à l\u27utilisation des données par des acteurs publics ou privés et à la maîtrise par les individus de leurs informations personnelles ; reconnaissance de nouvelles garanties - droit d\u27accès, neutralité, loyauté - jugées indispensables à l\u27exercice des libertés à l\u27ère numérique ; reconnaissance en droit des communs et du domaine public informationnels

New pathway to bypass the 15O waiting point

We propose the sequential reaction process $^{15}$O($p$,$\gamma)(\beta^{+}$)$^{16}$O as a new pathway to bypass of the $^{15}$O waiting point. This exotic reaction is found to have a surprisingly high cross section, approximately 10$^{10}$ times higher than the $^{15}$O($p$,$\beta^{+}$)$^{16}$O. These cross sections were calculated after precise measurements of energies and widths of the proton-unbound $^{16}$F low lying states, obtained using the H($^{15}$O,p)$^{15}$O reaction. The large $(p,\gamma)(\beta^{+})$ cross section can be understood to arise from the more efficient feeding of the low energy wing of the ground state resonance by the gamma decay. The implications of the new reaction in novae explosions and X-ray bursts are discussed.Comment: submitte