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Magnetism in atomically thin functional materials can be an important phenomenon for exploring two-dimensional magneto-optics. Magneto-optical experimental data have revealed significant Kerr signals in insulator thin films. Here, the magneto-optical Kerr effect of oxygen functionalized and doped hexagonal boron nitride (hBN) has been investigated by performing first-principles calculations. We calculated Kerr angle and Kerr ellipticity for functionalized hBN as an attention-drawn material. Moreover, increasing of oxygen doping percentage leads to the introduction of surface plasmon to hBN. Our findings show that the functionalized hBN can tolerate high-temperature conditions, keeping oxygen atoms bridge-bonded. These giant opto/magnetic responses of insulating 2D materials provide a platform for the potential designing of magneto-optical devices.

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The self-assembly of fibrils is a subject of intense interest, primarily due to its relevance to the formation of pathological structures. Some fibrils develop branches via the so-called secondary nucleation. In this paper, we use the master equation approach to model the kinetics of formation of branched fibrils. In our model, a branched fibril consists of one mother branch and several daughter branches. We consider five basic processes of fibril formation, namely, nucleation, elongation, branching, fragmentation, and dissociation of the primary nucleus of fibrils into free monomers. Our main focus is on the effect of the directionality of growth on the kinetics of fibril formation. We consider several cases. At first, the mother branch may elongate from one or from both ends, while the daughter branch elongates only from one end. We also study the case of branched fibrils with bidirectionally growing daughter branches, tangentially to the main stem, which resembles the intertwining process. We derive a set of ordinary differential equations for the moments of the number concentration of fibrils, which can be solved numerically. Assuming that the primary nucleus of fibrils dissociates with the fragmentation rate, in the limit of the zero branching rate, our model reproduces the results of a previous model that considers only the three basic processes of nucleation, elongation, and fragmentation. We also use the experimental parameters for the fibril formation of Huntingtin fragments to investigate the effect of unidirectional vs bidirectional elongation of the filaments on the kinetics of fibrillogenesis.

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Topological crystalline insulators (TCIs) are particularly one of the most fascinating materials in current research. The gapless surface states protected by the crystal point group symmetries in TCIs entail the emergence of nontrivial physics and can be tailored by controlling the external perturbations. This paper is devoted to a detailed analysis of the perturbation effects on the quantum phase of SnTe(001) surface states. Generically, surface states are gradually perturbed so that the gapless phase dies out. In doing so, a numerical study of the perturbed k[combining right harpoon above]·p[combining right harpoon above] model is accomplished by the linear response theory and the Green's function technique. The model is experimentally accessible. The system displays a commensurate breaking of the mirror invariance imposed by external perturbations such as strain, magnetic proximity effect/electric field/Zeeman magnetic field, Rashba spin-orbit coupling, and dilute charged impurity. The interesting behaviors are explained by the variation of the gap with the above-mentioned perturbations (invoking the opening of the gap) at Dirac cones corresponding to the TCI phase. For suitably tuned parameters, SnTe(001) surface states realize gapped phases. The synergy of perturbations is responsible for breaking down the topologically non-trivial character of SnTe and related alloys. Further, the conditions under which the variations of the parameters maintain the topological properties are discussed. These findings and predictions report that, besides a vast number of TCI applications, TCIs are versatile candidates for topological transistors with tunable ON and OFF states if appropriate tuning of the surface band gap can be performed experimentally.

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We theoretically address the electronic structure of mono- and simple bi-layer armchair graphene nanoribbons (AGNRs) when they are infected by extrinsic charged dilute impurity. This is done with the aid of the modified tight-binding method considering the edge effects and the Green's function approach. Also, the interplay of host and guest electrons are studied within the full self-consistent Born approximation. Given that the main basic electronic features can be captured from the electronic density of states (DOS), we focus on the perturbed DOS of lattices corresponding to the different widths. The modified model says that there is no metallic phase due to the edge states. We found that the impurity effects lead to the emergence of midgap states in DOS of both systems so that a semiconductor-to-semimetal phase transition occurs at strong enough impurity concentrations and/or impurity scattering potentials. The intensity of semiconductor-to-semimetal phase transition in monolayer (bilayer) ultra-narrow (realistic) ribbons is sharper than bilayers (monolayers). In both lattices, electron-hole symmetry breaks down as a result of induced-impurity states. The findings of this research would provide a base for future experimental studies and improve the applications of AGNRs in logic semiconductor devices in industry.

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The stability, optimized structure, and electronic gap of four diamondoid complexes, adamantane, C(10)H(16), diamantane, C(14)H(20), triamantane, C(18)H(24) and the T(d)-symmetry isomer of pentamantane, C(26)H(32), incorporating cage-centered small atoms and ions (X@cage, where X = H(+), Li(0,+), Be(0,+,2+), Na(0,+), Mg(0,2+), He, Ne, and F(-)) have been studied at the B3LYP hybrid level of theory. All adamantane complexes, except those encapsulating H(+) and Mg, are endohedral minima. In contrast no diamantane complexes are minima. A wide variety of atoms and ions can be encapsulated by triamantane and pentamantane molecules. The complexes are more stable for smaller and more highly charged metallic guest species. The electronic HOMO-LUMO gaps of diamondoid complexes are significantly affected by the inclusion of charged particles. The stability of the structures, the amount of the charges which are transferred between small particles and diamondoids cages, and the change in the HOMO-LUMO gaps of diamondoids are nearly the same for the corresponding possible complexes. All these features mostly depend on the charge, the size and the type of the encapsulated particle, and not on the type of diamondoid.