Mapping of Bernal and non-Bernal stacking domains in bilayer graphene using infrared nanoscopy

Abstract

Bilayer graphene (BLG) shows great potential as a new material for opto-electronic devices because its bandgap can be controlled by varying the stacking orders, as well as by applying an external electric field. An imaging technique that can visualize and characterize various stacking domains in BLG may greatly help in fully utilizing such properties of BLG. Here we demonstrate that infrared (IR) scattering-type scanning near-field optical microscopy (sSNOM) can visualize Bernal and non-Bernal stacking domains of BLG, based on the stacking-specific inter- and intra-band optical conductivities. The method enables nanometric mapping of stacking domains in BLG on dielectric substrates, augmenting current limitations of Raman spectroscopy and electron microscopy techniques for the structural characterization of BLG.

Experimental observation of ABCB stacked tetralayer graphene

“…At photon energies above 0.2 eV, s-SNOM gives access to the stacking-specific optical conductivities of FLG, and the scattering amplitude and phase values can be retrieved simultaneously. This allows to assign sub-diffraction FLG domains to stackings by recording images at specific photon energies [32,33]. Recently, it has been shown for IR nano-spectroscopy on bilayer graphene around the conductivity resonances at 0.39 eV that optical amplitude and phase scale with the characteristics of real and imaginary part of the conductivity [34].…”

Cyclophane with eclipsed pyrene units enables construction of spin interfaces with chemical accuracy

“…16 AA-stacked bilayer graphene has been a subject of theoretical interest, [17][18][19] but it has been observed only in limited cases in which it could be characterized sparingly. 17,[20][21][22][23][24][25][26] We hypothesized that such an AApacked graphene bilayer would exhibit interfacial magnetoresistance when placed in contact with a ferromagnetic electrode, as has been found at boundaries between zinc methyl phenalenyl molecules and cobalt. 9 Chemisorption of the lower aromatic group would form a hybrid molecular magnet, while the upper ring would act as a spin analyser because it retains sharp states with spin-polarization induced by p-p interactions.…”

Tunable s-SNOM for Nanoscale Infrared Optical Measurement of Electronic Properties of Bilayer Graphene

“…This method allows for the differentiation between several stacking order of graphene such as rhombohedral and Bernal stacked trilayer graphene 24 and Bernal and non-Bernal stacked BLG. 25 Furthermore, previous studies addressed the contrast between a monolayer and Bernal stacked BLG on top of a Si/SiO 2 substrate with the point dipole model. 25 At the single IR frequency of a HeNe-Laser of 0.366 eV these predictions could also be experimentally verified.…”

“…25 Furthermore, previous studies addressed the contrast between a monolayer and Bernal stacked BLG on top of a Si/SiO 2 substrate with the point dipole model. 25 At the single IR frequency of a HeNe-Laser of 0.366 eV these predictions could also be experimentally verified.…”

“…Since the amplitude and the phase of the scattered light are related to the complex optical conductivity or permittivity respectively, they can in principle be reconstructed from the measurement. This method allows for the differentiation between several stacking order of graphene such as rhombohedral and Bernal stacked trilayer graphene and Bernal and non-Bernal stacked BLG . Furthermore, previous studies addressed the contrast between a monolayer and Bernal stacked BLG on top of a Si/SiO 2 substrate with the point dipole model .…”