C-axis negative magnetoresistance and upper critical fieldof Bi2Sr2CaCu2O8

Abstract

The out-of-planeresistance and the resistive upper critical field of BSCCO-2212 single crystals with Tc0 ≃ 91–93 K havebeen measured in magnetic fieldsup to 50 T over a wide temperature range. The results are characterised by a positive linear magnetoresistance in the superconducting state and a negative linear magnetoresistance in the normal state. The zero-field normal-state c-axis resistance, the negative linear normal-state magnetoresistance, and thedivergent upper critical field Hc2(T) are explainedin the framework of the bipolaron theoryof superconductivity.