a-axis oriented epitaxial YBa2Cu3O7−x-PrBa2Cu3O7−y heterostructures

Abstract

We have grown YBa2Cu3O7−x-PrBa2Cu3O7−y heterostructures with the perovskite a axis normal to the surface of a variety of (001) oriented substrates using the pulsed laser deposition technique. X-ray diffraction studies indicate little or no formation of the traditional c-axis normal orientation usually nucleated on these substrates, while ion channeling, transmission electron microscopy (TEM), and Raman scattering studies reveal a highly ordered crystalline structure similar in quality to that obtained in the best c-axis oriented films. Superconducting transition temperatures, for current transport in the plane of the films, consistently exceed 80 K, but are probably lower than the optimum 92 K transition expected for YBa2Cu3O7−x due to the presence of growth twin boundaries between grains with the c axis oriented along the two substrate directions.

YBa/sub 2/Cu/sub 3/O/sub 7/(-δ) a-axis films and planar junctions

“…Mostly used are YBCO (self-template) and PBCO, because the latter tends more to a-axis growth [8]. The template layer must not be too thin in order to give a good stress relaxation, but a too thick one can lead to roughening.…”

Study of in-plane electrical transport anisotropy of a -axis oriented YBa2Cu3O7−δ nanodevices

“…The best reports refer instead to a-axis films grown on a PrBa 2 Cu 3 O 7−δ (PBCO) buffer layer on (100) SrLaGaO 4 (SLGO) substrates [10][11][12][13][14][15][16][17], that are also * floriana.lombardi@chalmers.se untwinned. Moreover, a-axis films have much smaller grains than c-axis films [2], which can give rise to rougher surfaces and complications in the realization of multilayer structures. As a matter of fact, the nanopatterning of a-axis films has also turned out to be quite challenging.…”

“…At the beginning of the 1990s, a-axis YBa 2 Cu 3 O 7−δ (YBCO) films attracted much attention because of the possibility to employ the longer a-b plane coherence length, ξ ab , for the realization of multilayer-based Josephson devices [1,2]. Nowadays, with the advancement of the nanotechnologies applied to HTSs, YBCO a-axis films would represent the natural choice for the realization of superconducting proximity-based hybrid systems such as superconductor-normal-conductor-superconductor (SNS) junctions.…”

Growth of [110] La2∕3Sr1∕3MnO3–YBa2Cu3O7 heterostructures

“…This can be achieved by growing either ͓100͔ / ͓010͔ or ͓110͔ oriented YBCO films. While the ͓100͔ / ͓010͔ and ͓110͔ YBCO oriented films on lattice matched substrates have been deposited successfully, [11][12][13] the growth of a FM-SC heterostructure or superlattice with the CuO 2 planes normal to the plane of the substrate is quite nontrivial.…”