Multilayer YBa2Cu3Ox-SrTiO3-YBa2Cu3Ox films for insulating crossovers

Abstract
We describe our procedure for fabricating YBa2Cu3Ox‐SrTiO3‐YBa2Cu3Ox thin‐film trilayer structures. Each film is grown in situ by excimer laser deposition onto a heated (100)MgO substrate. The geometrical configuration of each layer is defined by a metal mask; the vacuum chamber is opened between depositions to allow the targets and masks to be changed. The lower and upper YBa2Cu3Ox films in the best trilayer structure had transition widths of 1 and 3 K (10–90%), respectively, and transition temperatures (zero resistance) of 87 K. The resistance between the YBa2Cu3Ox films at 77 K was 108 Ω for an overlapping area of 0.2 mm2, corresponding to a SrTiO3 resistivity of 4×109 Ω cm.