Density-of-states fluctuation-induced negative out-of-plane magnetoresistance in overdoped Bi-2212

TL;DR

This study investigates the negative out-of-plane magnetoresistance in overdoped Bi-2212, attributing it to superconductive density-of-states fluctuations, and distinguishes it from in-plane behavior explained by d-wave superconductivity.

Contribution

It demonstrates that out-of-plane MR in overdoped Bi-2212 is driven by DOS fluctuations, while in-plane MR is explained without DOS contribution, highlighting different fluctuation mechanisms.

Findings

Negative out-of-plane MR is due to DOS fluctuations.

In-plane MR is explained by the Aslamazov-Larkin contribution.

Out-of-plane resistivity increases sharply near Tc.

Abstract

We analyzed the in-plane and out-of-plane magnetoresistance (MR) for overdoped Bi$_{1.6}$Pb$_{0.4}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ (Bi-2212) single crystals using superconductive fluctuation theory, which considers the density-of-states (DOS) contribution in layered superconductors with the conventional s-wave pairing state. The out-of-plane results are well reproduced by the theory, implying that the large, negative out-of-plane MR as well as the sharp increase in the zero-field out-of-plane resistivity $\rho_{c}$ near the superconducting transition temperature $T_c$ originate from the superconductive DOS fluctuation effect. On the other hand, the in-plane results are better reproduced without the DOS contribution (i.e., using only the Aslamazov-Larkin (AL) contribution), which may be explained in terms of the d-wave superconductivity of the layered superconductors.