Strain Engineering of Magneto-optical Properties in C3_3B/C3_3N van der Waals Heterostructure

Carbon-based bilayer van der Waals (vdW) materials are attracting much attention due to their predicted interesting physical properties. Here, we theoretically investigate electronic and optical properties of C$_3$B/C$_3$N vdW heterostructure (HTS) under external magnetic field and mechanical strain. The tight-binding model of the system is constructed to include the strain-induced modification of the hopping interactions. The influence of a uniform perpendicular magnetic field is included by using the Peierls substitution method. We observe the intriguing electronic and optical characteristics of the HTS under mechanical strain, covering the band inversion, alteration of band gap and optical gap, distortion of band-edge states, as well as significant enhancement of optical absorption. Furthermore, the interplay between external magnetic field and biaxial strain leads to exotic features of quantization and optical spectra. This work provides important information for the comprehension of the engineering of materials by external effects. Our study suggests that C$_3$B/C$_3$N vdW HTS is a promising candidate for next-generation electronic and optoelectronic devices

Magnetoplasmons in magic-angle twisted bilayer graphene

The magic-angle twisted bilayer graphene (MATBLG) has been demonstrated to exhibit exotic physical properties due to the special flat bands. However, exploiting the engineering of such properties by external fields is still in it infancy. Here we show that MATBLG under an external magnetic field presents a distinctive magnetoplasmon dispersion, which can be significantly modified by transferred momentum and charge doping. Along a wide range of transferred momentum, there exist special pronounced single magnetoplasmon and horizontal single-particle excitation modes near charge neutrality. We provide an insightful discussion of such unique features based on the electronic excitation of Landau levels quantized from the flat bands and Landau damping. Additionally, charge doping leads to peculiar multiple strong-weight magnetoplasmons. These characteristics make MATBLG a favorable candidate for plasmonic devices and technology applications

Polarizability and Impurity Screening for Phosphorene

Using a tight-binding Hamiltonian for phosphorene, we have calculated the real part of the polarizability and the corresponding dielectric function, Re[ ϵ q ω ], at absolute zero temperature (T = 0 K) with free carrier density 10 13 / cm 2 . We present results showing Re[ ϵ q ω ] in different directions of the transferred momentum q. When q is larger than a particular value which is twice the Fermi momentum kF, Re[ ϵ q ω ] becomes strongly dependent on the direction of q . We also discuss the case at room temperature (T = 300 K). These results which are similar to those previously reported by other authors are then employed to determine the static shielding of an impurity in the vicinity of phosphorene