Probing topological insulators surface states via plasma-wave Terahertz detection

TL;DR

This paper introduces a novel method using room-temperature Terahertz detection to directly probe topological surface states in topological insulators, enabling advanced applications in THz photonics.

Contribution

It demonstrates the first room-temperature THz detection mediated by plasma-wave oscillations on topological surface states of Bi2Te2.2Se0.8 flakes.

Findings

Successful room-temperature THz detection using TSS

Probing of plasma-wave oscillations on TSS

Potential for large-area THz imaging

Abstract

Topological insulators (TIs) represent a novel quantum state of matter, characterized by edge or surface-states, showing up on the topological character of the bulk wave functions. Allowing electrons to move along their surface, but not through their inside, they emerged as an intriguing material platform for the exploration of exotic physical phenomena, somehow resembling the graphene Dirac-cone physics, as well as for exciting applications in optoelectronics, spintronics, nanoscience, low-power electronics, and quantum computing. Investigation of topological surface states (TSS) is conventionally hindered by the fact that in most of experimental conditions the TSS properties are mixed up with those of bulk-states. Here, we devise a novel tool to unveil TSS and to probe related plasmonic effects. By engineering Bi2Te(3-x)Sex stoichiometry, and by gating the surface of nanoscale field-effect-transistors, exploiting thin flakes of Bi2Te2.2Se0.8 or Bi2Se3, we provide the first demonstration of room-temperature Terahertz (THz) detection mediated by over-damped plasma-wave oscillations on the "activated" TSS of a Bi2Te2.2Se0.8 flake. The reported detection performances allow a realistic exploitation of TSS for large-area, fast imaging, promising superb impacts on THz photonics.