Two overlaying isostructural two-dimensional crystals with slightly different lattice constants, or two equivalent crystals deposited on each other with a slight misalignment, produce a long-range quasi-periodic structure [1,2]

We investigate the effects of homogeneous and inhomogeneous deformations and edge disorder on the conductance of gated graphene nanoribbons. Under increasing homogeneous strain the conductance of such devices initially decreases before it acquires a resonance structure and, finally, becomes completely suppressed at higher strain. Edge disorder induces mode mixing in the contact regions, which can restore the conductance to its ballistic value. The valley-antisymmetric pseudomagnetic field induced by inhomogeneous deformations leads to the formation of additional resonance states, which originate either from the coupling into Fabry-Pérot states that extend through the system or from the formation of states that are localized near the contacts, where the pseudomagnetic field is largest. In particular, the n = 0 pseudo-Landau level manifests itself via two groups of conductance resonances close to the charge neutrality point.

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We consider eigenstates and magneto-optical transitions of free and donor-bound spin-singlet and spin-triplet charged magnetoexcitons in quasi-two-dimensional quantum wells. We show that the bright singlet state remains always bound while spin-triplet dark and bright states become unbound when the distance to the donor ion becomes smaller than certain critical values, which depend on the magnetic field strength. We demonstrate that main magneto-photoluminescence lines of free and donor-bound charged excitons exhibit very similar features. However, shake-up processes in photoluminescence of free trions are strictly prohibited. Therefore, shake-up transitions are distinct features indicating that symmetry-breaking mechanisms are present in the system.

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