Dirac Point Degenerate with Massive Bands at a Topological Quantum Critical Point

TL;DR

This paper investigates a topological phase transition in CoSb3 where Dirac and massive bands become degenerate at a critical point, revealing insights into topological quantum criticality without spin-orbit influence.

Contribution

It demonstrates the existence of a critical point in CoSb3 where Dirac and massive bands degenerate, advancing understanding of topological phase transitions in insulators.

Findings

Critical point features degenerate Dirac and massive bands.

Spin-orbit coupling does not affect the transition.

CoSb3 is near the topological critical point in nature.

Abstract

The quasi-linear bands in the topologically trivial skutterudite insulator CoSb$_3$ are studied under adiabatic, symmetry-conserving displacement of the Sb sublattice. In this cubic, time-reversal and inversion symmetric system, a transition from trivial insulator to topological point Fermi surface system occurs through a critical point in which massless (Dirac) bands are {\it degenerate} with massive bands. Spin-orbit coupling does not alter the character of the transition. The mineral skutterudite (CoSb$_3$) is very near the critical point in its natural state.