Magnetic-field-dependent quasiparticle energy relaxation in mesoscopic wires

In order to find out if magnetic impurities can mediate interactions between quasiparticles in metals, we have measured the effect of a magnetic field B on the energy distribution function f(E) of quasiparticles in two silver wires driven out-of-equilibrium by a bias voltage U. In a sample showing sharp distributions at B=0, no magnetic field effect is found, whereas in the other sample, rounded distributions at low magnetic field get sharper as B is increased, with a characteristic field proportional to U. Comparison is made with recent calculations of the effect of magnetic-impurities-mediated interactions taking into account Kondo physics.Comment: 4 pages, 3 figures, to be published in Physical Review Letter

Influence of Magnetic Field on Effective Electron-Electron Interactions in a Copper Wire

We have measured in a copper wire the energy exchange rate between quasiparticles as a function of the applied magnetic field. We find that the effective electron-electron interaction is strongly modified by the magnetic field, suggesting that magnetic impurities play a role on the interaction processes.Comment: latex anthore.tex, 8 files, 6 figures, 7 pages in: Proceedings of the XXXVIth Rencontres de Moriond `Electronic Correlations: From Meso- to Nano-physics' Les Arcs, France January 20-27, 2001 [SPEC-S01/027

Conductance fluctuations in metallic nanogaps made by electromigration

We report on low temperature conductance measurements of gold nanogaps fabricated by controlled electromigration. Fluctuations of the conductance due to quantum interferences and depending both on bias voltage and magnetic field are observed. By analyzing the voltage and magnetoconductance correlation functions we determine the type of electron trajectories generating the observed quantum interferences and the effective characteristic time of phase coherence in our device.Comment: 5 pages, 4 figures, to appear in J. Appl. Phy

Constriction – Construction, a short history of specialised wearing apparel for athletic activities from the fourteenth century to nineteenth century

During the twentieth century, clothing permits a real freedom of bodily movement. However, when examining past athletic activity, we must take into account the period approach to the body: liberty of movement is at the same time controlled by morality, gestures and clothing. The French term “tenue” initially referred to behaviour, but since the end of the eighteenth century concerns the manner of dressing, and later by extension, the “dignity of conduct”. In the past times concerned with “sporting” activities such as the HEMA (Historical European Martial Arts), physical appearance is affected by rules of etiquette imposed by morality and civility. From the Middle Ages to the nineteenth century, each period offers a different overview of the dress standards in relation to the different approaches to corporal identity, and the constriction first necessary for military activities becomes indivisible from the moral and physical construction. As a practitioner of the 21st century, the question raises about our relationship, not only with our bodies but also with past cultures. As demonstrated by some concrete examples, if it is desired to fully approach the ancient practices, it is therefore necessary to also adopt the garment, in the same way as the accessories

Cold electron Josephson transistor

A superconductor-normal metal-superconductor mesoscopic Josephson junction has been realized in which the critical current is tuned through normal current injection using a symmetric electron cooler directly connected to the weak link. Both enhancement of the critical current by more than a factor of two, and supercurrent suppression have been achieved by varying the cooler bias. Furthermore, this transistor-like device demonstrates large current gain $\sim$20) and low power dissipation

Intensity of Coulomb Interaction between quasiparticles in diffusive metallic wires

The energy dependence and intensity of Coulomb interaction between quasiparticles in metallic wires is obtained from two different methods: determination of the temperature dependence of the phase coherence time from the magnetoresistance, and measurements of the energy distribution function in out-of-equilibrium situations. In both types of experiment, the energy dependence of the Coulomb interaction is found to be in excellent agreement with theoretical predictions. In contrast, the intensity of the interaction agrees closely with theory only with the first method, whereas an important discrepancy is found using the second one. Different explanations are proposed, and results of a test experiment are presented.Comment: Submitted to Solid States Communication

Density of states in a superconductor carrying a supercurrent

We have measured the tunneling density of states (DOS) in a superconductor carrying a supercurrent or exposed to an external magnetic field. The pair correlations are weakened by the supercurrent, leading to a modification of the DOS and to a reduction of the gap. As predicted by the theory of superconductivity in diffusive metals, we find that this effect is similar to that of an external magnetic field.Comment: To be published in Physical Review Letter

Tomonaga-Luttinger physics in electronic quantum circuits

In one-dimensional conductors, interactions result in correlated electronic systems. At low energy, a hallmark signature of the so-called Tomonaga-Luttinger liquids (TLL) is the universal conductance curve predicted in presence of an impurity. A seemingly different topic is the quantum laws of electricity, when distinct quantum conductors are assembled in a circuit. In particular, the conductances are suppressed at low energy, a phenomenon called dynamical Coulomb blockade (DCB). Here we investigate the conductance of mesoscopic circuits constituted by a short single-channel quantum conductor in series with a resistance, and demonstrate a proposed link to TLL physics. We reformulate and establish experimentally a recently derived phenomenological expression for the conductance using a wide range of circuits, including carbon nanotube data obtained elsewhere. By confronting both conductance data and phenomenological expression with the universal TLL curve, we demonstrate experimentally the predicted mapping between DCB and the transport across a TLL with an impurity.Comment: 9p,6fig+SI; to be published in nature comm; v2: mapping extended to finite range interactions, added discussion and SI material, added reference