Spin-helical transport in normal and superconducting topological insulators

TL;DR

This paper reviews recent theoretical and experimental advances in electron transport phenomena in topological insulators, highlighting their unique spin-helical surface states and potential for topological spin electronics.

Contribution

It provides a focused overview of key transport phenomena in 2D and 3D topological insulators, including quantum spin Hall effect and topological superconductivity, with insights into practical applications.

Findings

Topologically protected surface states exhibit spin-momentum locking.

Observation of quantum spin Hall effect in HgTe quantum wells.

Presence of Majorana states in topological superconducting phases.

Abstract

In a topological insulator (TI) the character of electron transport varies from insulating in the interior of the material to metallic near its surface. Unlike, however, ordinary metals, conducting surface states in TIs are topologically protected and characterized by spin helicity whereby the direction of the electron spin is locked to the momentum direction. In this paper we review selected topics regarding recent theoretical and experimental work on electron transport and related phenomena in two-dimensional (2D) and three-dimensional (3D) TIs. The review provides a focused introductory discussion of the quantum spin Hall effect in HgTe quantum wells as well as transport properties of 3DTIs such as surface weak antilocalization, the half-integer quantum Hall effect, s + p-wave induced superconductivity, superconducting Klein tunneling, topological Andreev bound states and related Majorana midgap states. These properties of TIs are of practical interest, guiding the search for the routes towards topological spin electronics.