Mott Transition vs Multicritical Phenomenon of Superconductivity and Antiferromagnetism -- Application to $\kappa$-(BEDT-TTF)$_2$X --

TL;DR

This paper theoretically investigates the complex relationship between the Mott transition, superconductivity, and antiferromagnetism, revealing phase diagrams and fluctuation effects relevant to organic conductors like $$-(BEDT-TTF)$_2$X.

Contribution

It introduces an Ising-type order parameter for the Mott transition and analyzes the interplay with SC and AF, including fluctuation effects leading to first-order transitions.

Findings

Mean-field phase diagrams of the interplay are derived.

Fluctuation effects often induce first-order phase transitions.

Predictions for physical behaviors near the Mott critical point are provided.

Abstract

Interplay between the Mott transition and the multicritical phenomenon of d-wave superconductivity (SC) and antiferromagnetism (AF) is studied theoretically. We describe the Mott transition, which is analogous to a liquid-gas phase transition, in terms of an Ising-type order parameter $\eta$. We reveal possible mean-field phase diagrams produced by this interplay. Renormalization group analysis up to one-loop order gives flows of coupling constants, which in most cases lead to fluctuation-induced first-order phase transitions even when the SO(5) symmetry exists betwen the SC and AF. Behaviors of various physical quantities around the Mott critical point are predicted. Experiments in $\kappa$-(BEDT-TTF)$_2$X are discussed from this viewpoint.