Abstract
We have found the correlation between nanoscopic phase separation in the copper-oxygen planes of YBCO and TlBCCO and the transport and magnetic properties of these materials in the a-b planes such as: the temperature dependence of the critical current density J
c
( T ), the temperature dependence of the superfluid density n
s
( T )∝1/λ
2
( T ) at low temperatures, the temperature dependence of the normalized logarithmic relaxation rate S(T), and the dependence of the effective energy barrier against vortex motion on the current density U
eff
( J ). These properties are controlled by the ratio of the amount of an underdoped filamentary phase to that of an optimally doped one.