Transport phenomena in three-dimensional system close to the magnetic quantum critical point: The conserving approximation with the current vertex corrections

TL;DR

This paper investigates anomalous transport behaviors near antiferromagnetic quantum critical points in three-dimensional systems, emphasizing the crucial role of current vertex corrections (CVC) in explaining experimental observations.

Contribution

It demonstrates that CVC significantly enhance Hall and Nernst coefficients near the AF QCP, providing a theoretical explanation for experimental anomalies in 3D heavy fermion systems.

Findings

Hall and Nernst coefficients increase due to CVC near AF QCP

Hot points and cold lines form in 3D systems from strong AF fluctuations

CVC effects are crucial regardless of system dimensionality

Abstract

It is known that various transport coefficients strongly deviate from conventional Fermi-liquid behaviors in many electron systems which are close to antiferromagnetic (AF) quantum critical points (QCP). For example, Hall coefficients and Nernst coefficients in three-dimensional heavy fermion CeCoIn5 and CeCu6-xAux increase strikingly at low temperatures, whose overall behaviors are similar to those in high-Tc cuprates. These temperature dependences are too strong to explain in terms of the relaxation time approximation. To elucidate the origin of these anomalous transport phenomena in three-dimensional systems, we study the current vertex corrections (CVC) based on the fluctuation exchange (FLEX) approximation, and find out decisive role of the CVC. The main finding of the present paper is that the Hall coefficient and the Nernst coefficient strongly increase thanks to the CVC in the vicinity of the AF QCP, irrespective of dimensionality. We also study the relaxation time of quasi-particles, and find that "hot points" and "cold lines" are formed in general three-dimensional systems due to strong AF fluctuations.