Theory of topological quantum phase transitions in 3D noncentrosymmetric systems

TL;DR

This paper develops a comprehensive theory for topological quantum phase transitions in 3D noncentrosymmetric systems, highlighting conditions for direct insulator-insulator transitions and analyzing anisotropic critical behaviors.

Contribution

It introduces a general framework for understanding topological phase transitions in 3D systems without inversion symmetry, including conditions for direct transitions and critical point properties.

Findings

Direct topological insulator-insulator transition possible with accidental band crossing.

At the quantum critical point, energy dispersion is quadratic in one direction and linear in others.

Thermodynamic and transport properties exhibit unusual temperature dependence and anisotropy.

Abstract

We have constructed a general theory describing the topological quantum phase transitions in 3D systems with broken inversion symmetry. While the consideration of the system's codimension generally predicts the appearance of a stable metallic phase between the normal and topological insulators, it is shown that a direct topological phase transition between two insulators is also possible when an accidental band crossing (ABC) occurs along directions with high crystalline symmetry. At the quantum critical point (QCP), the energy dispersion becomes quadratic along one direction while the dispersions along the other two orthogonal directions are linear, which manifests the zero chirality of the band touching point (BTP). Due to the anisotropic dispersion at QCP, various thermodynamic and transport properties show unusual temperature dependence and anisotropic behaviors.