Photocurrent measurements in topological insulator ${\text{Bi}}_2{\text{Se}}_3$ nanowires

Abstract

Circular photogalvanic currents are a promising new approach for spin-optoelectronics. To date, such currents have only been induced in topological insulator flakes or extended films. It is not clear whether they can be generated in nanodevices. In this paper, we demonstrate the generation of circular photogalvanic currents in ${\text{Bi}}_2{\text{Se}}_3$ nanowires. Each nanowire shows topological surface states. Here, we generate and distinguish the different photocurrent contributions via the driving light wave. We separate the circular photogalvanic currents from those due to thermal Seebeck effects, through controlling the laser light polarization. The results reveal a spin-polarized surface-Dirac electron flow in the nanowires arising from spin-momentum locking and spin-orbit effects. The second photocurrent contribution described in this letter is caused by the thermal Seebeck effect. By scanning the photocurrent, it can be spatially resolved; upon reversing the gradient direction along the nanowire, the photocurrent changes its sign, and close to the gold contacts, the amplitudes of the different photocurrent contributions are affected by the proximity to the contacts. In the center of the nanowires, where the effects from the gold contact/ topological insulator stacks vanish, the spin-polarized current remains constant along the nanowires. This opens up a new method of all-optical spin current generation in topological insulator nanowires and hybrid structures for nanoscale spin-orbitronics.

arXiv comment5 pages, 4 figures

References in corpus (18)

• Topological Insulators
• $Z_2$ Topological Order and the Quantum Spin Hall Effect
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Control over topological insulator photocurrents with light polarization
• Ultrafast photocurrents at the surface of the three-dimensional topological insulator ${\mathrm{Bi}}_2{\mathrm{Se}}_3$
• Electronic Structure of the Topological Insulator Bi2Se3 Using Angle-Resolved Photoemission Spectroscopy: Evidence for a Nearly Full Surface Spin Polarization
• Ultrafast helicity control of surface currents in topological insulators with near-unity fidelity
• Room temperature high frequency transport of Dirac fermions in epitaxially grown Sb_2Te_3 based topological insulators
• Enhanced photogalvanic current in topological insulators via Fermi energy tuning
• Photon Drag Effect in (Bi${}_{1-x}$Sb${}_x$)${}_2$Te${}_3$ Three Dimensional Topological Insulators
• Ultrafast Electron Dynamics in the Topological Insulator Bi2Se3 Studied by Time-Resolved Photoemission Spectroscopy
• Spin photocurrents and circular photon drag effect in (110)-grown quantum well structures
• Robust surface electronic properties of topological insulators: Bi2Te3 films grown by molecular beam epitaxy
• Thermoelectric performance of classical topological insulator nanowires
• Opto-Electronic Characterization of Three Dimensional Topological Insulators
• Spin-momentum locked interaction between guided photons and surface electrons in topological insulators
• The Interplay of Topological Surface and Bulk Electronic States in Bi2Se3
• Observation of spin Nernst photocurrents in topological insulators

Cited by in corpus (3)

• Highly superlinear photogalvanic effects in (Bi${}_{0.3}$Sb${}_{0.7}$)${}_2$(Te${}_{0.1}$Se${}_{0.9}$)${}_3$: Probing 3D topological insulator surface states at room temperature
• The impact of metallic contacts on spin-polarized photocurrents in topological insulator ${\text{Bi}}_2{\text{Se}}_3$ nanowires
• Introducing antiferromagnetic ordering on the surface states of Bi2Se3 topological insulator by Europium doping