Epitaxial Sr2(AlTa)O6 films as buffer layers on MgO for YBa2Cu3O7−x thin film growth

Abstract
Sr2(AlTa)O6 thin films (2000–3000 Å) have been deposited on MgO (001) substrates using pulsed laser deposition (PLD). X‐ray‐diffraction analysis shows that the Sr2(AlTa)O6 grows with the c axis highly oriented normal to the substrate plane and very good in‐plane epitaxy. The subsequently deposited YBa2Cu3O7−x films using PLD on Sr2(AlTa)O6 buffered MgO substrates exhibit excellent epitaxial growth with a narrow rocking curve width and a small φ scan peak width. The critical temperature Tc0 of 90–92 K has been achieved reproducibly and the critical current density is over 2.7×106 A/cm2 at 77 K.