Ultrafast spin-polarization control of Dirac fermions in topological insulatorsстатья
Статья опубликована в высокорейтинговом журнале
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 17 июня 2016 г.
Аннотация:Three-dimensional topological insulators (TIs) are characterized by spin-polarized Dirac-cone surface states that are protected from backscattering by time-reversal sym- metry. Manipulating ultrafast spin dynamics of Dirac fermions in TIs might play an imperative role in revolutionizing future applications of these materials in spintronics. Control of the spin polarization of topological surface states (TSSs) using femtosec- ond light pulses is one alternative which opens up novel perspectives for the generation and manipulation of dissipationless surface spin currents on ultrafast timescales. Using time-, spin-, and angle-resolved spectroscopy, we directly monitor for the first time the ultrafast response of the spin polarization of photoexcited TSSs to circularly-polarized femtosecond pulses of infrared light and opposite helicity. We achieve all-optical switch- ing and full control of the transient out-of-plane spin polarization of photoexcited TSSs, 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 novel optospintronic applications at ultimate speeds.