Epitaxial films of high Tc oxide superconductors Y1Ba2Cu3O7 grown on SrTiO3 by molecular beam epitaxy

Orientation ordered high-Tc oxide films of Y1Ba2Cu3O7 were prepared by molecular beam epitaxy on SrTiO3 substrates. A combination of effusion cells and e-beam evaporators was used with the addition of an oxygen jet. The superconducting phase is formed by further O2 anneal at temperatures greater than about 800 C. For SrTiO3 (100), the Y1Ba2Cu3O7 films grow in the orientation of either the c-axis or the a-axis perpendicular to the film plane. Films with predominant c-perpendicular orientation exhibit a high degree of crystalline order with a rocking curve 0.3 deg wide. The Jc is about two times higher than those with the a-perpendicular orientation of a comparable Tc (R = 0). For a typical film of 9000 A thickness, a Tc (R = 0) of 87 K, and a Jc of 70,000 A/sq cm at 77 K were reproducibly achieved. For SrTiO3 (110), X-ray showed twinning of (110) and (103) orientations in Y1Ba2Cu3O7, thus precluding the observation of anisotropy expected for the in-plane axes of 001 and 110 lines. 8 references