Pseudogap in Bi2Sr2CaCu2O8+delta studied by measuring anisotropic susceptibilities and out-of-plane transport.

We find in the Bi2Sr2CaCu2O8+delta system that the characteristic temperatures T*chi [below which the uniform susceptibilities chiabT (Hperpendicularc) and chicT (Hparallelc) decrease] and T*(rhoc) [below which the out-of-plane resistivity rhoc(T) shows typical upturn] coincide for all doping levels. We attribute the T dependence of chi's and rhoc to the anomalous (pseudogapped) density of states (DOS) in high- Tc cuprates. Furthermore, the anisotropy in the T dependence of chi's is universal, i.e., chic approximately 1.6chiab, showing that there is only a single T-dependent component in the chi's. This implies that the Curie-like behavior (dchi/dT<0) observed in overdoped samples is also caused by a DOS effect.