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Smectic A (SmA) liquid crystals can be viewed as model systems for lamellar structures. They bridge the study of broken orientational symmetry, the statistical mechanics of membranes, and the long-range periodic order in crystals. Among others, they provide an arena to systematically study the effects of nonlinear elasticity. We demonstrated that a nonlinear energy description is required which is not captured in the classical Landau-de Gennes-Ginsburg model in order to explain the observed layer spacing of highly curved SmA layers. Using X-ray diffraction, we quantitatively determined the dilation of bent layers distorted by antagonistic anchoring. We showed that combined X-ray measurements and theoretical modeling allow for the quantitative determination of the number of curved smectic layers and their thickness in dilated regions.

DOI: https://doi.org/10.1103/PhysRevLett.134.018101

To visualize the intrinsic band structure of armchair graphene nanoribbon and verify theories, the terminus is covalently bonded to Au-coated tip. Tunneling spectroscopies with these suspended nanoribbons exhibit symmetric onsets of conduction and valence bands around zero bias. From these results, a value of 2.78 eV for the band gap is determined which agrees very well with theoretical calculations.

Interestingly, the formation of C—Au bond suppresses Schottky contact resistance which is one of the essential prerequisites for future nanoribbon electronics.

DOI: https://onlinelibrary.wiley.com/doi/10.1002/pssr.202470030