The Role of Spin-Orbit Coupling in Topological Insulators

Abstract

Spin-orbit coupling (SOC) plays a central role in the emergence of topological insulators (TIs), where insulating bulk states coexist with conducting edge or surface states protected by time-reversal symmetry. This article reviews the theoretical foundation of SOC-induced band inversion, its effect on topological invariants, and its critical role in the formation of robust, dissipationless surface transport in TIs. By analyzing the mechanism of SOC across various material classes, we elucidate how its strength governs topological phase transitions. The review also outlines the experimental verification of SOC phenomena and the future potential of SOC-engineered topological quantum devices.