Pr. Apte et al., SURFACE-RESISTANCE, RESIDUAL LOSSES, AND GRANULARITY IN AG-DOPED YBA2CU3O7-DELTA THIN-FILMS, Journal of applied physics, 75(8), 1994, pp. 4258-4260
We have studied microwave surface resistance R(s) and residual resista
nce R(res) in undoped and Ag-doped laser ablated thin-film YBa2Cu3O7-d
elta mirostrip resonators On LaAlO3 substrates. While the undoped film
s showed a frequency dependence R(s) is-proportional-to f(p), where p
= 1.9 +/- 1, Ag-doped films showed p = 1.6 +/- 1 and 1.4 +/- 1 for 5 a
nd 10 wt % Ag doping, respectively. Lower p values and higher R(res) o
bserved in Ag-doped films indicate a metallic contribution. However, t
he advantage of Ag-doped films has been shown to be at 77 K at which t
hey not only have a lower R(s) but also a low dR(s)/dT, thus making th
em superior to undoped films for microwave devices operating at 77 K.