Paramagnetic effect in YBaCuO grain boundary junctions

A detailed investigation of the magnetic response of YBaCuO grain boundary Josephson junctions has been carried out using both radio-frequency measurements and Scanning SQUID Microscopy. In a nominally zero-field-cooled regime we observed a paramagnetic response at low external fields for 45 degree asymmetric grain boundaries. We argue that the observed phenomenology results from the d-wave order parameter symmetry and depends on Andreev bound states.Comment: To be published in Phys. Rev.

The use of thermal initiator to make organic bulk heterojunction solar cells with a good percolation path

10.1063/1.2965468Applied Physics Letters934-APPL

Improvement in the hole collection of polymer solar cells by utilizing gold nanoparticle buffer layer

10.1016/j.cplett.2008.01.013Chemical Physics Letters4531-373-76CHPL

Surface morphology and in-plane-epitaxy of SmBa₂Cu₃O₇_-δ films on SrTiO₃ (001) substrates studied by STM and grazing incidence x-ray diffraction

The surface morphology and in-plane epitaxy of thin films of SmBa2Cu3O7−δ (SmBCO) grown on SrTiO3 (001) substrates with various thicknesses have been investigated by scanning tunneling microscopy (STM) and grazing incidence x-ray diffraction (GIXRD). As revealed by GIXRD, SmBCO films as thick as 500 Å grow pseudomorphically on SrTiO3 (001) surfaces, in comparison with a maximum of 130 Å for YBCO. This is probably due to a better lattice match of SmBCO (εa=1.2%, εb=−0.5%) compared to YBCO (εa=2.0%, εb=0.7%) with the SrTiO3 substrate. Three different types of surface morphology were observed by STM with increasing film thickness h: a) 2D growth for h<hc1, b) columnar structures for hc1 <h<hc2, c) spiral growth for h>hc2. With GIXRD, a density modulation is observed in the films with a thickness below hc2. For thicker films above hc2, introduction of screw dislocations leads to spiral growth

Characterization and in situ-fluorescence diagnostic of the deposition od YBa_2Cu_30_7-x thin films by pseudo-spark electron beam ablation

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