The infrared spectra of ABC-stacking tri- and tetra-layer graphenes studied by first-principles calculations

The infrared absorption spectra of ABC-stacking tri- and tetra-layer graphenes are studied using the density functional theory. It is found that they exhibit very different characteristic peaks compared with those of AB-stacking ones, caused by the different stacking sequence and interlayer coupling. The anisotropy of the spectra with respect to the direction of the light electric field is significant. The spectra are more sensitive to the stacking number when the electric field is perpendicular to the graphene plane due to the interlayer polarization. The high sensitivities make it possible to identify the stacking sequence and stacking number of samples by comparing theory and experiment.Comment: 7 pages, 5 figure

Detecting Electronic States at Stacking Faults in Magnetic Thin Films by Tunneling Spectroscopy

Co islands grown on Cu(111) with a stacking fault at the interface present a conductance in the empty electronic states larger than the Co islands that follow the stacking sequence of the Cu substrate. Electrons can be more easily injected into these faulted interfaces, providing a way to enhance transmission in future spintronic devices. The electronic states associated to the stacking fault are visualized by tunneling spectroscopy and its origin is identified by band structure calculations.Comment: 4 pages, 4 figures; to be published in Phys. Rev. Lett (2000

Stacking-symmetry governed second harmonic generation in graphene trilayers

Crystal symmetry plays a central role in governing a wide range of fundamental physical phenomena. One example is the nonlinear optical second harmonic generation (SHG), which requires inversion symmetry breaking. Here we report a unique stacking-induced SHG in trilayer graphene, whose individual monolayer sheet is centrosymmetric. Depending on layer stacking sequence, we observe a strong optical SHG in Bernal (ABA) stacked non-centrosymmetric trilayer, while it vanishes in rhombohedral (ABC) stacked one which preserves inversion symmetry. This highly contrasting SHG due to the distinct stacking symmetry enables us to map out the ABA and ABC crystal domains in otherwise homogeneous graphene trilayer. The extracted second order nonlinear susceptibility of the ABA trilayer is surprisingly large, comparable to the best known 2D semiconductors enhanced by excitonic resonance. Our results reveal a novel stacking order induced nonlinear optical effect, as well as unleash the opportunity for studying intriguing physical phenomena predicted for stacking-dependent ABA and ABC graphene trilayers.Comment: To appear in Science Advance

The interlaminar fracture toughness of woven graphite/epoxy composites

The interlaminar fracture toughness of 2-D graphite/epoxy woven composites was determined as a function of stacking sequence, thickness, and weave pattern. Plain, oxford, 5-harness satin, and 8-harness satin weaves of T300/934 material were evaluated by the double cantilever beam test. The fabric material had a G (sub Ic) ranging from 2 to 8 times greater than 0 degrees unidirectional T300/934 tape material. The interlaminar fracture toughness of a particular weave style was dependent on whether the stacking sequence was symmetric or asymmetric and, in some cases, on the fabric orientation

Macro-mechanical and microscopic study of the fatigue damage behaviour of a carbon fabric/PPS thermoplastic composite

This manuscript elaborates on the tension-tension fatigue behaviour of a carbon fabric reinforced polyphenylene sulphide. The damage behaviour will be investigated by (i) conducting fatigue experiments, in order to determine the macroscopic behaviour such as permanent deformation and stiffness degradation and (ii) a microscopic investigation using both optical and scanning electron (SEM) microscopy. It may be concluded that for the [(0°,90°)]4s stacking sequence the material does not show significant stiffness reduction and that only limited permanent deformation is present. Furthermore, the material shows very brittle failure behaviour. For the [(+45°,-45°)]4s stacking sequence, however, a different behaviour manifests itself. Stiffness reduction does occur and there is a significant permanent deformation, in combination with a high rise in temperature, above the softening temperature of the matrix