Properties of Y-Ba-Cu-O thin films with ordered defect structure: ${\mathrm{Y}}_2{\mathrm{Ba}}_4{\mathrm{Cu}}_8{\mathrm{O}}_{20-x}$

Properties of both unfaulted and faulted $c$-axis-oriented ${\mathrm{Y}}_2{\mathrm{Ba}}_4{\mathrm{Cu}}_8{\mathrm{O}}_{20-x}$ thin films are reported. Their superconducting transition temperatures are 81 and 93 K, respectively. This implies that the precise ordering of copper-oxygen layers in $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ is not crucial for the high $T_c$. ${\mathrm{Y}}_2{\mathrm{Ba}}_4{\mathrm{Cu}}_8{\mathrm{O}}_{20-x}$ exhibits lower resistivity and lower Hall coefficient than $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$. The extra copper-oxygen layers seem to play an important role in the normal state.