Article (Scientific journals)
Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field
Georgi, Alexander; Nemes-Incze, Peter; Carrillo-Bastos, Ramon et al.
2017In Nano Letters, 17, p. 2240−2245
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Keywords :
graphene; STM; strain; pseudomagnetic field; pseudospin polarization; valley filter
Abstract :
[en] One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudomagnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudomagnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudomagnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene’s pseudospin due to a strain induced pseudomagnetic field, in analogy to the alignment of a real spin in a magnetic field. We reveal this sublattice symmetry breaking by tunably straining graphene using the tip of a scanning tunneling microscope. The tip locally lifts the graphene membrane from a SiO2 support, as visible by an increased slope of the I(z) curves. The amount of lifting is consistent with molecular dynamics calculations, which reveal a deformed graphene area under the tip in the shape of a Gaussian. The pseudomagnetic field induced by the deformation becomes visible as a sublattice symmetry breaking which scales with the lifting height of the strained deformation and therefore with the pseudomagnetic field strength. Its magnitude is quantitatively reproduced by analytic and tight-binding models, revealing fields of 1000 T. These results might be the starting point for an effective THz valley filter, as a basic element of valleytronics.
Disciplines :
Physics
Author, co-author :
Georgi, Alexander;  RWTH Aachen University > II. Institute of Physics B
Nemes-Incze, Peter;  RWTH Aachen University > II. Institute of Physics B
Carrillo-Bastos, Ramon;  Universidad Autónoma de Baja California > Facultad de Ciencias
Faria, Daiara;  Universidade Federal Fluminense, Niterói, Rio de Janeiro > Instituto de Física
Kusminskiy, Silvia Viola;  Freie Universität Berlin
Zhai, Dawei;  Ohio University, Athens, Ohio > Department of Physics and Astronomy
Schneider, Martin;  Freie Universität Berlin
Subramaniam, Dinesh;  RWTH Aachen University > II. Institute of Physics B
Mashoff, Torge;  Johannes Gutenberg-Universität Mainz
Freitag, Nils M.;  RWTH Aachen University > II. Institute of Physics B
Liebmann, Marcus;  RWTH Aachen University > II. Institute of Physics B
Pratzer, Marco;  RWTH Aachen University > II. Institute of Physics B
Wirtz, Ludger ;  University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
Woods, Colin R.;  University of Manchester > School of Physics and Astronomy
Gorbachev, Roman V.;  University of Manchester > School of Physics and Astronomy
Cao, Yang;  University of Manchester > School of Physics and Astronomy
Novoselov, Kostya S.;  University of Manchester > School of Physics and Astronomy
Sandler, Nancy;  Ohio University, Athens, Ohio > Department of Physics and Astronomy
Morgenstern, Markus;  RWTH Aachen University > II. Institute of Physics B
More authors (9 more) Less
External co-authors :
yes
Language :
English
Title :
Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field
Publication date :
17 February 2017
Journal title :
Nano Letters
ISSN :
1530-6992
Publisher :
American Chemical Society, Washington, United States - District of Columbia
Volume :
17
Pages :
2240−2245
Peer reviewed :
Peer Reviewed verified by ORBi
Focus Area :
Physics and Materials Science
FnR Project :
FNR7490149 - 20 Electric Transport And Superconductivity In Transition Metal Dichalcogenides Nanolayers, 2013 (01/02/2014-31/01/2019) - Ludger Wirtz
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