Link between antiferromagnetism and superconductivity probed by nuclear spin relaxation in organic conductors

TL;DR

This paper investigates the relationship between antiferromagnetism and superconductivity in organic conductors, using a microscopic model and renormalization group approach to explain experimental NMR relaxation data.

Contribution

It introduces a unified microscopic framework that describes the crossover from antiferromagnetism to superconductivity and explains anomalous nuclear relaxation rates in organic conductors.

Findings

Scaling theory shows pairing correlations enhance antiferromagnetic correlations.

Enhanced magnetic correlations cause Curie-Weiss behavior in NMR relaxation.

The model successfully describes the temperature dependence of nuclear spin-lattice relaxation.

Abstract

The interdependence of antiferromagnetism and superconductivity in the Bechgaard salts series of organic conductors is examined in the light of the anomalous temperature dependence of the nuclear spin-lattice relaxation rate. We apply the renormalization group approach to the electron gas model to show that the crossover from antiferromagnetism to superconductivity along with the anomalous nuclear relaxation rate of the Bechgaard salts can be well described within a unified microscopic framework. For sizable nesting deviations of the Fermi surface, scaling theory reveals how pairing correlations enhance short-range antiferromagnetic correlations via magnetic Umklapp scattering over a large part of the metallic phase that precedes superconductivity. These enhanced magnetic correlations are responsible for the Curie-Weiss behavior observed in the NMR relaxation rate.