A Comparative Study of Nonlinear Microwave Properties in YBa2Cu3O7, TlBaCaCuO and HgBaCaCuO Microstrip Resonators

Microwave nonlinearity is investigated in several high-temperature superconductors (HTS) including YBa2Cu3O7, TlBa2CaCu2O7, Tl2Ba2CaCu2O8, TlBa2Ca2Cu3O9 and HgBa2CaCu2O6+delta microstrip resonators. The critical power, above which nonlinearity becomes a serious concern, was compared with the dc critical current density J(c) at temperatures above 77 K. When plotted at the real temperature scale, P-c and J(c) for each HTS system follow a similar trend near T-c, indicating that a similar mechanism of magnetic pinning limits both P-c and J(c). This result suggests that a better P-c may be achieved in HTS films of enhanced magnetic pinning.