INPUT COILS FOR YBA2CU3O7 FLUX-TRANSFORMERS

Input coils for flux transformers at 77 K are fabricated in a YBa2Cu3O7/SrTiO3/YBa(2)Cu3O(7) trilayer technology. The films are deposited on SrTiO3(100) substrates by KrF excimer laser ablation and patterned ex situ by standard photolithography and argon ion-beam etching. Input coils with 10 turns and linewidths down to 10 mu m were prepared and exhibit zero resistance temperatures up to 84 K and critical currents of 0.7 mA at 77 K. Separate crossovers and via-contacts were fabricated on the same chip with critical currents of l(c)(77 K) = 1 mA (crossover with 10 mu m linewidth) and l(c)(77 K) = 40 mA (via-contact). The insulation resistance for the 200 nm thick SrTiO3 layer between upper and lower line in a crossover is R(77 K) = 590 k Omega.