Superconducting thin-film multiturn coils of YBA2Cu3O7-x

We describe a technique for fabricating superconducting thin-film multiturn coils from the high-temperature superconductor YBa2Cu3O7−x. We have built 10-turn and 19-turn square spiral coils, 1 mm on a side, that are suitable for coupling to a thin-film dc superconducting quantum interference device. The coils are constructed with a three-layer crossover technology using SrTiO3 as an insulator. Each layer is deposited in situ with a pulsed excimer laser, and is patterned with shadow masks or photoresist and an Ar ion mill. The best coil had a transition temperature of approximately 82 K, and a critical current at 77 K of 1.4 mA, corresponding to a critical current density of 2×104 A cm−2.