Fingerprint of dynamical charge/spin correlations in the tunneling spectra of colossal magnetoresistive manganites

We present temperature-dependent scanning tunneling spectroscopy measurements on $La_{1-x}Ca_{x}MO_{3}$ ($x\sim0.33$) films with different degrees of biaxial strain. A depletion in normalized conductance around the Fermi level is observed both above and below the insulator-to-metal transition temperature $T_{MI}$, for weakly as well as highly-strained films. This pseudogap-like depletion globally narrows on cooling. The zero-bias conductance decreases on cooling in the insulating phase, reaches a minimum close to $T_{MI}$ and increases on cooling in the metallic phase, following the trend of macroscopic conductivity. These results support a recently proposed scenario in which dynamical short-range antiferromagnetic/charge order correlations play a preeminent role in the transport properties of colossal magnetoresistive manganites [R. Yu \textit{et al}., Phys. Rev. B \textbf{77}, 214434 (2008)].Comment: 9 pages, 4 figure

Inclusive Prompt Photon Production in Hadronic Final States of e+e−e^+e^- Annihilation

We provide complete analytic expressions for the inclusive prompt photon production cross section in hadronic final states of $e^+e^-$ annihilation reactions through one-loop order in quantum chromodynamics perturbation theory. Computed explicitly are direct photon production through first order in the electromagnetic strength $\alpha_{em}$ and the quark-to-photon and gluon-to-photon fragmentation contributions through first order in the strong coupling $\alpha_s$. The full angular dependence of the cross sections is displayed, separated into transverse $(1 +\cos ^2\theta _\gamma)$ and longitudinal $(\sin ^2\theta_\gamma)$ components, where $\theta_\gamma$ specifies the direction of the photon with respect to the $e^+e^-$ collision axis. We discuss extraction of fragmentation functions from $e^+e^-$ data.Comment: 40 pages, RevTex, 30 figures in postscript available in a separate fil

Growth and superconducting properties of (Sr_1−xCa_x)RuO₃ / DyBa₂Cu₃O₇ hetero-structures

We report on the growth of SrRuO₃/DyBa₂Cu₃O₇ multilayers and investigations of proximity coupling in these structures. These films have been prepared by magnetron sputtering onto (100) SrTiO₃. Measurements of activation energies for flux motion in field perpendicular to the DyBa₂Cu₃O₇ a-b plane show a progressive increase of the coupling as the SrRuO₃ barrier is reduced

Growth and properties of SrCuO₂ and (Sr_1-xNd_x)CuO₂ epitaxial thin films

Thin films of the infinite layer compound (Sr1−x Ndx)CuO2 have been grown on (100) SrTiO3 substrates by RF reactive magnetron sputtering. Four-circle x-ray diffractometry reveals that (Sr,Nd)CuO2 thin films can be epitaxially grown with (001) orientation. Four-point transport measurements show resistance drops in some as-grown films of Sr1−xNdxCuO2 with x=0.11, 0.12 at temperatures ranging from 27 K to 35 K