Light-Field-Driven Currents in Graphene

Date

Aug 5, 2016

Time

11:00 AM - 12:00 PM

Speaker

Takuya Higuchi (Universität Erlangen-Nürnberg)

Language

en

Main Topic

Physik

Other Topics

Physik

Host

CMT seminars

Description

When electrons in crystalline solids are placed under an external electric field comparable to the internal field, they exhibit their quantum mechanical wave nature such as Zener tunneling. Advances in ultrashort-pulsed laser enable us to generate such a strong field confined within a few cycles of optical oscillations, which is employed to seek for strong-field phenomena in solids. So far the main experimental target is optically transparent materials with wide band gaps to avoid (multi-)photon absorption. Here we experimentally show that a characteristic strong-field interaction is found even in a gapless metallic system: a monolayer graphene. Light-induced currents in graphene show a clear dependence of the carrier-envelope phase (CEP) of the laser pulses, which is evidence of the contribution of the optical field-driven dynamics of electrons. A comparison with theory reveals that the interference of electron wave functions distributed via inter-band tunnelling and intra-band motion determines the direction and amplitude of the current, also known as Landau-Zener-Stückelberg interferometry. These results drastically broaden the scope of light-field control of electrons in conducting solids that is essential to achieve light-field-driven electronics.

Last modified: Aug 5, 2016, 9:40:12 AM