Competing orders in the Dirac-like electronic structure and the non-linear sigma model with the topological terms

TL;DR

This paper explores the interplay of competing order parameters in Dirac-like electronic systems, highlighting their duality and how their correlation functions reveal the nature of quantum phase transitions.

Contribution

It introduces the concept of dual order parameters in Dirac systems and analyzes their correlation functions near quantum critical points, providing new insights into quantum fluctuations.

Findings

Dual order parameters exhibit complementary correlation behaviors.

Fluctuations of one order enhance the correlations of its dual.

Correlation functions can diagnose the nature of quantum phase transitions.

Abstract

The Dirac-like electronic structure can host a large number of competing orders in the form of mass terms. In particular, two different order parameters can be said to be dual to each other, when a static defect in one of them traps a quantum number (or "charge") of the other. We discuss that such complementary nature of the pair of the order parameters shows up in their correlation functions and dynamical properties when a quantum phase transition is driven by fluctuations of the one of the order parameters. Approaching the transition from the disordered (paramagnetic) side, the order parameter correlation function at the critical point is reduced, while such fluctuations enhance the correlation of the dual order parameter. Such complementary behaviors in the correlation function can be used to diagnose the nature of quantum fluctuations that is the driving force of the quantum phase transition.