Ultrafast spin-polarization control of Dirac fermions in topological insulators

Sánchez-Barriga, J.; Golias, E.; Varykhalov, A.; Braun, J.; Yashina, L. V.; Schumann, R.; Minár, J.; Ebert, H.; Kornilov, O. and Rader, O. (2016): Ultrafast spin-polarization control of Dirac fermions in topological insulators. In: Physical Review B, Vol. 93, No. 15, 155426

Abstract

Three-dimensional topological insulators (TIs) are characterized by spin-polarized Dirac-cone surface states that are protected from backscattering by time-reversal symmetry. Control of the spin polarization of topological surface states (TSSs) using femtosecond light pulses opens novel perspectives for the generation and manipulation of dissipationless surface spin currents on ultrafast time scales. Using time-, spin-, and angle-resolved spectroscopy, we directly monitor the ultrafast response of the spin polarization of photoexcited TSSs to circularly polarized femtosecond pulses of infrared light. We achieve all-optical switching of the transient out-of-plane spin polarization, which relaxes in about 1.2 ps. Our observations establish the feasibility of ultrafast optical control of spin-polarized Dirac fermions in TIs and pave the way for optospintronic applications at ultimate speeds.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Subjects: 500 Science > 540 Chemistry
• ISSN: 2469-9950
• Language: English