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

TL;DR

This study investigates giant magnetoresistance effects in Bi-2212 single crystals, revealing significant normal state MR attributed to magnetic pair-breaking of preformed pairs, with results supporting a Bose-Einstein condensation model.

Contribution

It provides the first detailed measurement of large normal state magnetoresistances in Bi-2212, linking them to preformed pairs and Bose-Einstein condensation behavior.

Findings

Both in-plane and out-of-plane MRs exceed orbital contributions by two orders of magnitude.

Resistive upper critical fields show non-BCS temperature dependence.

MR behavior is explained by magnetic pair-breaking of preformed pairs.

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.