Author:

Keywords:

upper critical-field, magnetic-field, negative magnetoresistance, single-crystals, doping dependence, temperature, superconductors, resistivity, la2-xsrxcuo4, cuprate, Science & Technology, Physical Sciences, Physics, Condensed Matter, Physics, UPPER CRITICAL-FIELD, NEGATIVE MAGNETORESISTANCE, MAGNETIC-FIELD, DOPING DEPENDENCE, TEMPERATURE, RESISTIVITY, CUPRATE, cond-mat.supr-con, 01 Mathematical Sciences, 02 Physical Sciences, Fluids & Plasmas, 49 Mathematical sciences, 51 Physical sciences

Abstract:

Magnetoresistance (MR) of Bi-2212 single crystals with T-c approximate to 87 - 92 K is studied in pulsed magnetic fields tip to 50 T 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.