In this paper, we present a detailed investigation of the structural, electronic, and optical properties of pristine, nitrogenated, and fluorinated MgO monolayers using ab initio calculations.

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Pressure controls electronic and optical properties of monolayer MoS2 with organic molecular adsorption.

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In practice, modifying the fundamental properties of low-dimensional materials should be realized before incorporating them into nanoscale devices. In this paper, we systematically investigate the nitrogen (N) doping and oxygen vacancy (OV) effects on the electronic and magnetic properties of the beryllium oxide (BeO) monolayer using first-principles calculations. Pristine BeO single layer is a non-magnetic insulator with an indirect K–Γ gap of 5.300 eV. N doping induces a magnetic semiconductor nature, where the spin-up and spin-down band gaps depend on the dopant concentration and N–N separation. Creating one OV leads to the energy gap reduction of 31.06% with no spin-polarization, which is due to the abundant 2p electrons of the Be atoms nearest the OV site. The further increase to two OVs and varying the OV–OV distance affect the band gap values, however the spin independence is retained. The magnetic semiconducting behavior is also obtained by the simultaneous N doping and OV presence. Calculations reveal significant magnetization of the BeO@1N, BeO@2N-n, BeO@NOV-n systems, which is produced mainly by the spin-up N–2p state. Except for the BeO@NOV-1 and BeO@NOV-2, whose magnetic properties are created by the spin-up 2p state of the Be atoms closest to the OV site. The variation of the N–N and N–OV distances keeps the ferromagnetic ordering in the BeO@2N and BeO@NOV layers. Results presented herein may propose efficient methods to artificially modify the physical properties of BeO monolayer, leading to the formation of novel two-dimensional (2D) materials for optoelectronic and spintronic applications.

General one-loop contributions to the decay processes $$H\rightarrow f\bar{f}\gamma $$ H → f f ¯ γ and its applications are presented in this paper. We consider all possible contributions of the additional heavy vector gauge bosons, heavy fermions, and charged (also neutral) scalar particles propagating in Feynman loop diagrams. Therefore, analytic results are valid in a wide class of models beyond the Standard Model. Analytic formulas for the form factors are expressed in terms of Passarino-Veltman functions in the standard notations of . Hence, the decay rates can be evaluated numerically by using this package. The computations are then applied to the cases of the Standard Model, $$U(1)_{B-L}$$ U ( 1 ) B - L extension of the Standard Model as well as Two Higgs Doublet Model. Phenomenological results for all the above models are studied. We observe that the effects of new physics are sizable contributions and these can be probed at future colliders.

Chemical functionalization of low-dimensional materials has been widely employed to create new multifunctional materials with novel properties. In this paper, we present the results of the fluorination effects on the structural, electronic, magnetic, and optical properties of the BeO monolayer. Materials stability is examined by means of the phonon dispersion curves and binding energy. Significant structural changes of the BeO monolayer are induced by the fluorination. The pristine single layer possesses a wide indirect K − Γ band gap of 5.23 eV with no spin-polarization. Either half-metallic or magnetic semiconductor structures with important ferromagnetism can be induced by the half-fluorination, and a total magnetic moment of 1 μ B may be obtained. The full-fluorination produces a magnetism-free material, however causes the indirect-direct gap transition and a considerable reduction of the energy gap to 0.97 eV. The fluorination enhances the BeO monolayer optical properties in the low energy regime, and also the interaction with the light polarized in the z-direction. Our simulations suggest that the fluorination may be an effective approach to tune the BeO single layer physical properties producing new materials, which are expected to find prospective applications in the spintronic and optoelectronic nano-devices.

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