Enhanced critical current density of YBa2Cu3Ox films grown on   Nd1/3Eu1/3Gd1/3Ba2Cu3Ox with nano-undulated surface morphology
  We report a simple and easily controllable method where a nano-undulated surface morphology of Nd1/3Eu1/3Gd1/3Ba2Cu3Ox (NEG) films leads to a substantial increase in the critical current density in superconducting YBa2Cu3Ox (YBCO) films deposited by pulsed laser deposition on such NEG layers. The enhancement is observed over a wide range of fields and temperatures. Transmission electron microscopy shows that such YBCO films possess a high density of localized areas, typically 20 x 20 nm2 in size, where distortion of atomic planes give rotational (2 to 5 degrees) moire patterns. Their distribution is random and uniform, and expected to be the origin of the enhanced flux pinning. Magneto-optical imaging shows that these films have excellent macroscopic magnetic uniformity. 
R. L. Meng (1), T. H. Johansen (1 and 2), I. A. Rusakova (1), A.   Baikalov (1), D. Pham (1), F. Chen (1), Z. Y. Zuo (1), C....