Many-body instabilities and mass generation in slow Dirac materials

TL;DR

This paper investigates the many-body instabilities and potential mass generation in topological Kondo insulators with slow Dirac surface states, revealing conditions for spin and charge density wave orders.

Contribution

It introduces a tight-binding model to analyze how heavy bulk states influence surface Dirac fermions, highlighting possible strong coupling effects and ordered phases.

Findings

Identification of parameter regions with spin density wave order.

Identification of parameter regions with charge density wave order.

Demonstration of strong coupling effects due to small Fermi velocities.

Abstract

Some Kondo insulators are expected to possess topologically protected surface states with linear Dirac spectrum, the topological Kondo insulators. Because the bulk states of these systems typically have heavy effective electron masses, the surface states may exhibit extraordinarily small Fermi velocities that could force the effective fine structure constant of the surface states into the strong coupling regime. Using a tight-binding model we study the many-body instabilities of these systems and identify regions of parameter space in which the system exhibits spin density wave, and charge density wave order.