Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X02: Focus Session: Probing and Controlling Matter with Intense Light
8:00 AM–10:00 AM,
Friday, June 4, 2021
Chair: Loren Greenman, Kansas State University
Abstract: X02.00006 : Light-Induced Valleytronics In Pristine Graphene
9:36 AM–9:48 AM
Live
Presenter:
Gopal Dixit
(Department of Physics, IIT Bombay India)
Authors:
Gopal Dixit
(Department of Physics, IIT Bombay India)
Mrudul Muraleedharan Shylaja
(Department of Physics, IIT Bombay India)
Misha Ivanov
(Max-Born Institute Berlin, Germany)
Alvaro Jimenez-Galan
(Max-Born Institute Berlin, Germany)
One of the most exciting features of graphene and gapped graphene materials is the electrons extra degree of freedom, the valley pseudospin, associated with populating the local minima K and K in the lowest conduction band of the Brillouin zone. This extra degree of freedom can encode, process and store quantum information, opening the field of valleytronics [2]. In gapped graphene materials, valley selectivity is achieved by a pump pulse resonant with the bandgap and with matching helicity to the Berry curvature of the material [3]. The vanishing bandgap makes graphene unsuited for such resonant valley-selective excitations - a disappointing conclusion given its exceptional transport properties.
In the present work, we show that valley-selective excitation in graphene can be achieved in an all-optical- means [4]. This non-resonant valley polarization mechanism uses a combination of two counter-rotating circularly polarized fields, the fundamental and its second harmonic. Controlling the relative phase between the two colours allows us to select the valleys where the electron-hole pairs and higher-order harmonics are generated. The tailored field allows one to both break the symmetry between the adjacent carbon atoms and also exploit the anisotropic regions in the valleys, taking advantage of the fact that the energy landscape of the valleys are mirror images of each other. Our proposal offers an all-optical route to valleytronics in pristine graphene.
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