Coherent and incoherent bands in La and Rh doped Sr3Ir2O7

In Sr2IrO4 and Sr3Ir2O7, correlations, magnetism and spin-orbit coupling compete on similar energy scales, creating a new context to study metal-insulator transitions (MIT). We use here Angle-Resolved photoemission to investigate the MIT as a function of hole and electron doping in Sr3Ir2O7, obtained respectively by Ir/Rh and Sr/La substitutions. We show that there is a clear reduction as a function of doping of the gap between a lower and upper band on both sides of the Fermi level, from 0.2eV to 0.05eV. Although these two bands have a counterpart in band structure calculations, they are characterized by a very different degree of coherence. The upper band exhibits clear quasiparticle peaks, while the lower band is very broad and loses weight as a function of doping. Moreover, their ARPES spectral weights obey different periodicities, reinforcing the idea of their different nature. We argue that a very similar situation occurs in Sr2IrO4 and conclude that the physics of the two families is essentially the same

Scanning tunneling spectroscopy study of the proximity effect in a disordered two-dimensional metal

The proximity effect between a superconductor and a highly diffusive two-dimensional metal is revealed in a scanning tunneling spectroscopy experiment. The in situ elaborated samples consist of superconducting single crystalline Pb islands interconnected by a nonsuperconducting atomically thin disordered Pb wetting layer. In the vicinity of each superconducting island the wetting layer acquires specific tunneling characteristics which reflect the interplay between the proximity-induced superconductivity and the inherent electron correlations of this ultimate diffusive two-dimensional metal. The observed spatial evolution of the tunneling spectra is accounted for theoretically by combining the Usadel equations with the theory of dynamical Coulomb blockade; the relevant length and energy scales are extracted and found in agreement with available experimental dataWe thank Hermann Grabert for useful discussions. This work was supported by grants from the University Pierre et Marie Curie (UPMC) ‘‘Emergence’’ and by CNRS Ph.D. Grant (L. S.-G.). J. C. C. and F. S. B. acknowledge financial support from the Spanish MICINN (Contracts No. FIS2011-28851-C02-01 and No. FIS2011-28851- C02-02

Spectre d'absorption dans l'infrarouge lointain d'un cristal de benzamide

Far infrared absorption by a benzamide single crystal is studied with polarized light between 15 and 250 cm-1 at 80 and 300 K. We have observed the two internal modes expected below 200 cm-1. The other active frequencies are assigned to lattice modes and can be explained by dimerization. We find that the translational frequencies of the two dimers of the unit cell are located at 25.5 ; 28 and 36.5 cm-1 at 300 K and shift to 29 ; 32 and 42 cm-1 at 80 K.L'absorption d'un cristal de benzamide dans l'infrarouge lointain est étudiée en lumière polarisée de 15 à 250 cm-1 aux températures de 80 et 300 K. Nous avons mis en évidence les deux modes internes attendus au-dessous de 200 cm-1. Les autres fréquences observées sont attribuées aux modes de réseau et s'expliquent par l'association des molécules en dimères. En particulier les fréquences des vibrations de translation des deux dimères de la maille sont situées à 25,5 ; 28 et 36,5 cm-1 à 300 K et à 29 ; 32 et 42 cm-1 à 80 K

Projection neurons of the mormyrid electrosensory lateral line lobe : Morphology, immunohistochemistry and synaptology

Contains fulltext : 22801___.PDF (publisher's version ) (Open Access