96 research outputs found

    Hall Anomaly and Vortex-Lattice Melting in Superconducting Single Crystal YBa2Cu3O7-d

    Full text link
    Sub-nanovolt resolution longitudinal and Hall voltages are measured in an ultra pure YBa2Cu3O7-d single crystal. The Hall anomaly and the first-order vortex-lattice melting transition are observed simultaneously. Changes in the dynamic behavior of the vortex solid and liquid are correlated with features of the Hall conductivity sxy. With the magnetic field oriented at an angle from the twin-boundaries, the Hall conductivity sharply decreases toward large negative values at the vortex-lattice melting transition.Comment: 6 pages, 2 figures included, Postscript, to appear in Phys. Rev. Let

    Structural and optical characterization of InP/InGaAsP distributed Bragg reflectors grown by CBE

    No full text
    High quality InP/InGaAsP Distributed Bragg Reflectors (DBRs) are a key element in Vertical Cavity Surface Emitting Laser (VCSELs) for long wavelength (1.55 mu m) applications [1-3]. Because of the small index difference between InP and InGaAsP, more than 30 periods are needed to obtain reflectivities above 99 %, which makes it a challenge for the crystal growth technique. In this paper we present the structural and optical characteristics of such DBRs grown by Chemical Beam Epitaxy (CBE) at high growth rates that comply with the requirements for the integration in long wavelength VCSELs
    • 

    corecore