Anisotropic resistivity of the antiferromagnetic insulator Bi2Sr2ErCu2O8

The anisotropic resistivities of Bi2Sr2Ca1-xErxCu2O8 Single crystals were m easured and analysed from 4.2 to 500 K with special interest taken in the p arent antiferromagnetic insulator with x = 1.0. Although the resistivity is semiconducting along both the in-plane and out-of-plane directions, the te mperature dependences are found to be significantly different. As a result, the resistivity ratio for x = 1.0 exhibits a broad maximum near room tempe rature. The electric conduction in the parent antiferromagnetic insulators is different from that in other semiconductors, and is as unconventional as that in high-temperature superconductors.