# Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi2Se3

@article{Braun2016UltrafastPA, title={Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi2Se3}, author={Lukas Braun and Gregor Mussler and A. Hruban and Marcin Konczykowski and T. Schumann and Martin Wolf and Markus M{\"u}nzenberg and Luca Perfetti and Tobias Kampfrath}, journal={Nature Communications}, year={2016}, volume={7} }

Three-dimensional topological insulators are fascinating materials with insulating bulk yet metallic surfaces that host highly mobile charge carriers with locked spin and momentum. Remarkably, surface currents with tunable direction and magnitude can be launched with tailored light beams. To better understand the underlying mechanisms, the current dynamics need to be resolved on the timescale of elementary scattering events (∼10 fs). Here, we excite and measure photocurrents in the model…

## 113 Citations

Surface State-Dominated Photoconduction and THz Generation in Topological Bi2Te2Se Nanowires

- Materials Science, MedicineNano letters
- 2017

It is demonstrated that the long surface lifetime of Bi2Te2Se nanowires allows for the access of surface states by a pulsed photoconduction scheme and that there is a prevailing bolometric response of the surface states.

Helicity dependent photocurrent in electrically gated (Bi1−xSbx)2Te3 thin films

- Physics, MedicineNature Communications
- 2017

It is demonstrated that the directional photocurrent is due to the asymmetric optical transitions between topological surface states and bulk states, which is important for engineering opto-spintronic devices that rely on optical steering of spin and charge currents.

Reversible engineering of topological insulator surface state conductivity through optical excitation

- Physics, MedicineNanotechnology
- 2021

This work illustrates a route to reversibly manipulate the surface states through optical excitation, shedding light into utilizing topological surface states for quantum optoelectronics.

Impact of ultrafast transport on the high-energy states of a photoexcited topological insulator

- PhysicsPhysical Review B
- 2018

Ultrafast dynamics in three-dimensional topological insulators (TIs) opens new routes for increasing the speed of information transport up to frequencies thousand times faster than in modern…

Ultrafast Zero-Bias Surface Photocurrent in Germanium Selenide: Promise for Terahertz Devices and Photovoltaics.

- Materials Science, MedicineACS applied materials & interfaces
- 2019

Experimental demonstration of THz emission by the surface shift current in bulk GeSe crystals puts this 2D material forward as a candidate for next-generation shift current photovoltaics, nonlinear photonic devices, and THz sources.

Observation of spin Nernst photocurrents in topological insulators

- Physics
- 2018

The theoretical prediction of topological insulators in 2007 triggered tremendous interest. They are of fundamental interest because of their topological twist in k-space, which comes along with…

Spin Hall photoconductance in a three-dimensional topological insulator at room temperature

- Physics, MedicineNature Communications
- 2017

Three-dimensional topological insulators are a class of Dirac materials, wherein strong spin-orbit coupling leads to two-dimensional surface states, wherein a helical, bias-dependent photoconductance at the lateral edges of topological Bi2Te2Se platelets for perpendicular incidence of light is observed.

Photocurrent measurements in topological insulator Bi 2 Se 3 nanowires

- Physics, Materials Science
- 2020

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…

A cascading nonlinear magneto-optical effect in topological insulators

- Materials Science, MedicineScientific Reports
- 2018

The helicity dependence of the time-resolved Kerr rotation exhibits a robust change in periodicity at a critical thickness, from which it is possible to predict the formation of a Dirac cone in a film several quintuple layers thick.

Subcycle observation of lightwave-driven Dirac currents in a topological surface band

- Physics, MedicineNature
- 2018

Time- and angle-resolved photoemission spectroscopy reveals how Dirac fermions in the band structure of the topological surface state of Bi2Te3 are accelerated by the carrier wave of a terahertz-frequency light pulse, which may greatly improve the understanding of electron dynamics and strong-field interaction in solids.

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