Momentum alignment of photoexcited carriers in graphene: The route to optovalleytronics

A linearly polarized excitation is shown to create a strongly anisotropic distribution of photoex­cited carriers in graphene, where the momenta of photoexcited carriers are aligned preferentially normal to the polarization plane. This hitherto overlooked effect offers an experimental tool to gen­era...

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Main Authors: Hartmann, Richard R., Portnoi, Mikhail E.
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Published: Animo Repository 2011
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Online Access:https://animorepository.dlsu.edu.ph/faculty_research/7395
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spelling oai:animorepository.dlsu.edu.ph:faculty_research-81012022-10-19T01:11:30Z Momentum alignment of photoexcited carriers in graphene: The route to optovalleytronics Hartmann, Richard R. Portnoi, Mikhail E. A linearly polarized excitation is shown to create a strongly anisotropic distribution of photoex­cited carriers in graphene, where the momenta of photoexcited carriers are aligned preferentially normal to the polarization plane. This hitherto overlooked effect offers an experimental tool to gen­erate highly directional photoexcited carriers which could assist in the investigation of "direction­dependant phenomena" in graphene-based nanostructures. The depolarization of hot photolumi­nescence (HPL) has been used with great success to study relaxation processes in conventional 2D systems. In such systems the alignment is due to the spin-orbit interaction for photoexcited holes, whereas in graphene, it is due to the pseudo-spin. Namely, the ratio of the two components of the spinor-like graphene wavefunction depends on the electron momentum which influences the optical transition selection rules. By comparing the depolarization from successive phonon replicas, the mechanisms for phonon relaxation in graphene can be studied. Furthermore, studying the depolar­ization of HPL in a magnetic field (the Hanle effect) allows one to obtain momentum relaxation times of hot electrons. The effect of momentum alignment in graphene provides a contact-free method of characterizing energy and momentum relaxation. Our analysis of momentum alignment in the high frequency regime shows that a linearly polarized excitation allows the spatial separation of carriers belonging to different valleys, therefore opening the door to an optical means of controlling valley polarization (optovalleytronics) and quantum computing in graphene 2011-01-12T08:00:00Z text https://animorepository.dlsu.edu.ph/faculty_research/7395 Faculty Research Work Animo Repository Graphene Electronic excitation Relaxation phenomena Valleytronics Physics
institution De La Salle University
building De La Salle University Library
continent Asia
country Philippines
Philippines
content_provider De La Salle University Library
collection DLSU Institutional Repository
topic Graphene
Electronic excitation
Relaxation phenomena
Valleytronics
Physics
spellingShingle Graphene
Electronic excitation
Relaxation phenomena
Valleytronics
Physics
Hartmann, Richard R.
Portnoi, Mikhail E.
Momentum alignment of photoexcited carriers in graphene: The route to optovalleytronics
description A linearly polarized excitation is shown to create a strongly anisotropic distribution of photoex­cited carriers in graphene, where the momenta of photoexcited carriers are aligned preferentially normal to the polarization plane. This hitherto overlooked effect offers an experimental tool to gen­erate highly directional photoexcited carriers which could assist in the investigation of "direction­dependant phenomena" in graphene-based nanostructures. The depolarization of hot photolumi­nescence (HPL) has been used with great success to study relaxation processes in conventional 2D systems. In such systems the alignment is due to the spin-orbit interaction for photoexcited holes, whereas in graphene, it is due to the pseudo-spin. Namely, the ratio of the two components of the spinor-like graphene wavefunction depends on the electron momentum which influences the optical transition selection rules. By comparing the depolarization from successive phonon replicas, the mechanisms for phonon relaxation in graphene can be studied. Furthermore, studying the depolar­ization of HPL in a magnetic field (the Hanle effect) allows one to obtain momentum relaxation times of hot electrons. The effect of momentum alignment in graphene provides a contact-free method of characterizing energy and momentum relaxation. Our analysis of momentum alignment in the high frequency regime shows that a linearly polarized excitation allows the spatial separation of carriers belonging to different valleys, therefore opening the door to an optical means of controlling valley polarization (optovalleytronics) and quantum computing in graphene
format text
author Hartmann, Richard R.
Portnoi, Mikhail E.
author_facet Hartmann, Richard R.
Portnoi, Mikhail E.
author_sort Hartmann, Richard R.
title Momentum alignment of photoexcited carriers in graphene: The route to optovalleytronics
title_short Momentum alignment of photoexcited carriers in graphene: The route to optovalleytronics
title_full Momentum alignment of photoexcited carriers in graphene: The route to optovalleytronics
title_fullStr Momentum alignment of photoexcited carriers in graphene: The route to optovalleytronics
title_full_unstemmed Momentum alignment of photoexcited carriers in graphene: The route to optovalleytronics
title_sort momentum alignment of photoexcited carriers in graphene: the route to optovalleytronics
publisher Animo Repository
publishDate 2011
url https://animorepository.dlsu.edu.ph/faculty_research/7395
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