1D quantum transport in the even-chain spin-ladder compound Sr2.5Ca11.5Cu24O41 and YBa2Cu4O8

The temperature dependence of the resistivity rho(T) of the novel Sr2-5Ca11.5Cu24O41 ladder compound under hydrostatic pressure of up to 8 GPa has been explained by assuming that the relevant length scale for electrical transport is given by the magnetic correlation length related to the opening of a spin-gap in a 1D even-chain spin-ladder (1D-SL). The pressure dependence of the gap was extracted by applying this model to rho(T) data obtained at different pressures. The rho(T) dependence of the underdoped cuprate YBa2Cu4O8 demonstrates a remarkable scaling with the rho(T) of the 1D-SL compound Sr2.5Ca11.5Cu24O41. This scaling: implies that underdoped cuprates at T-c < T < T* ase in the 1D regime and their pseudo-gap below T* is the spin-gap in the even-chain 1D-SL formed at T < T* in these materials.