No abstract

No abstract

No abstract

We have grown a-axis oriented YBa2Cu3O7−y (YBCO) films on LaSrGaO4 (LSGO) (100) substrates with (100) oriented seed layer of PrBa2Cu3O7−x (PBCO) using a pulsed laser deposition technique. PBCO films on LSGO (100) deposited even at ∼800 °C exhibits the a-axis orientation. In this temperature range, PBCO films on SrTiO3 (100) substrate exhibits the c-axis orientation. The YBCO film with a-axis orientation was grown on this PBCO(100) layer at a wide range of 650–800 °C. The YBCO films on PBCO free substrates have, on the other hand, c-axis orientation normal to the surface of the LSGO (100). We found that the preferred orientations of YBCO thin films can be controlled by the presence of PBCO films on LSGO substrate. For the a-axis orientated YBCO films, the resistance perpendicular to the c axis is 1/2 of that parallel to the c axis, suggesting the preferred orientation of c axis along the surface. The zero resistance superconducting transition temperature (Tc) of the films on the LSGO (100) and PBCO (100)/LSGO (100) substrates are 88.0 and 89.0 K, respectively.

As-grown YBa2Cu3O7−y (YBCO) thin films of 70 nm thickness have been prepared on LaSrGaO4(001), (100), and (110) single-crystal substrates at 700 °C using ArF laser ablation deposition. The c-axis oriented thin films with smooth surface morphology are obtained on LaSrGaO4 (001) and (100) substrates. The zero resistance temperatures (Tc) of the films on the (001) and (100) substrates are 90.0 K, and 88.1 K, respectively. On the (110) substrate, (110) YBCO planes grow epitaxially. The resistance perpendicular to the c axis in this film is 1/3 of that parallel to the c axis, showing Tc⊥=85.9 K and Tc∥=84.4 K, respectively. These results suggest that a LaSrGaO4 substrate having a low dielectric constant is an excellent substrate for the epitaxial growth and device application of high-Tc YBa2Cu3O7−y superconducting films.