Link between spin fluctuations and Cooper pairing in copper oxide superconductors

TL;DR

This study reveals a fundamental link between antiferromagnetic spin fluctuations and the pairing mechanism in high-temperature copper oxide superconductors, highlighting the role of T-linear scattering in their normal state.

Contribution

It demonstrates that T-linear scattering rate correlates with superconductivity and is caused by spin-fluctuation scattering, establishing a connection between AFM spin fluctuations and pairing in cuprates.

Findings

T-linear scattering surrounds the superconducting phase.

T-linear scattering persists at zero temperature when superconductivity is suppressed.

Spin-fluctuation scattering likely causes T-linear resistivity in cuprates.

Abstract

Although it is generally accepted that superconductivity (SC) is unconventional in the high- transition temperature copper oxides (high-Tc cuprates), the relative importance of phenomena such as spin and charge (stripe) order, SC fluctuations, proximity to a Mott insulator, a pseudogap phase, and quantum criticality are still a matter of great debate1. In electron-doped cuprates, the absence of an anomalous pseudogap phase in the underdoped region of the phase diagram2 and weaker electron correlations3,4, suggest that Mott physics and other unidentified competing orders are less relevant and that antiferromagnetic (AFM) spin fluctuations are the dominant feature. Here we demonstrate that a linear-temperature (T-linear) scattering rate - a key feature of the anomalous normal state properties of the cuprates - is correlated with the Cooper pairing (SC). Through a study of magnetotransport in thin films of the electron-doped cuprate La2 xCexCuO4 (LCCO), we show that an envelope of T-linear scattering surrounds the SC phase, and survives to zero temperature when superconductivity is suppressed by magnetic fields. Comparison with similar behavior found in organic superconductors5 strongly suggests that the T-linear resistivity is caused by spin-fluctuation scattering. Our results establish a fundamental connection between AFM spin fluctuations and the pairing mechanism of high temperature superconductivity in the cuprates.