Details

Autor(en) / Beteiligte

• Georgi, Alexander
• Nemes-Incze, Peter
• Carrillo-Bastos, Ramon
• Faria, Daiara
• Viola Kusminskiy, Silvia
• Zhai, Dawei
• Schneider, Martin
• Subramaniam, Dinesh
• Mashoff, Torge
• Freitag, Nils M
• Liebmann, Marcus
• Pratzer, Marco
• Wirtz, Ludger
• Woods, Colin R
• Gorbachev, Roman V
• Cao, Yang
• Novoselov, Kostya S
• Sandler, Nancy
• Morgenstern, Markus

Titel

Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field

Ist Teil von

• Nano letters, 2017-04, Vol.17 (4), p.2240-2245

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2017

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 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.