'Giant' normal state magnetoresistances of Bi\(_{2}\)Sr\(_{2}\)CaCu\(_{2}\)O\(_{8+\delta}\)

Abstract

Magnetoresistance (MR) of Bi-2212 single crystals with T\(_{c}\) \(\approx 87-92 K\) is studied in pulsed magnetic fields up to 50T along the c-axis in a wide temperature range. The negative out-of-plane and the positive in-plane MRs are measured in the normal state. Both MRs have similar magnitudes, exceeding any orbital contribution by two orders in magnitude. These are explained as a result of the magnetic pair-breaking of preformed pairs. Resistive upper critical fields H\(_{c2}\)(T) determined from the in-- and out-of-plane MRs are about the same. They show non-BCS temperature dependences compatible with the Bose-Einstein condensation field of preformed charged bosons.