Scaling behavior of the normal-state properties of the underdoped high-Tc cuprates

摘要

The scaling behavior of the normal state transport and magnetic properties of the underdoped cuprates as a function of T/T$-0$/ is now interpreted as an evidence for the opening of a pseudogap at T* approximately T$-0$/. To investigate the origin of the pseudogap, we have analyzed first the temperature dependence of the resistivity $rho@(T) of the novel Sr$-2.5$/Ca$-11.5$/Cu$-24$/O$-41$/ spin-ladder compound under hydrostatic pressure of up to 8 GPa. This $rho@(T) dependence has been successfully explained by assuming that the relevant length scale for electrical transport - the inelastic length - is given by the magnetic correlation length related to the opening of a spin-gap in a one- dimensional (1D) even-chain spin-ladder (1D-SL). As a next step, we compared the $rho@(T) curves of the SL compounds and underdoped cuprates. We have found that the $rho@(T) dependences of YBa$-2$/Cu$-4$/O$-8$/ and underdoped YBa$- 2$/Cu$-3$/O$-x$/ demonstrate a remarkable scaling with the $rho@(T) of the 1D-SL compound Sr$-2.5$/Ca$-11.5$/Cu$-24$/O$- 41$/. This scaling implies that the pseudo-gap below T* in underdoped YBa$-2$/Cu$-4$/O$-8$/ and YBa$-2$/Cu$-3$/O$-x$/ is the spin-gap in the even-chain 1D-SL formed at T less than T* in these materials. Therefore, at temperatures T$-c$/(x) less than T less than T*(x), underdoped cuprates are effectively in a 1D ('stripe') regime. A Josephson-like coupling of these stripes leads to a recovery of a 2D regime at low temperatures T approximately T$-c$/(x).