Unimpeded tunneling in graphene nanoribbons

We studied the Klein paradox in zigzag (ZNR) and anti-zigzag (AZNR) graphene nanoribbons. Due to the fact that ZNR (the number of lattice sites across the nanoribbon (N is even) and AZNR (N is odd) configurations are indistinguishable when treated by the Dirac equation, we supplemented the model with a pseudo-parity operator whose eigenvalues correctly depend on the sublattice wavefunctions for the number of carbon atoms across the ribbon, in agreement with the tight-binding model. We have shown that the Klein tunneling in zigzag nanoribbons is related to conservation of the pseudo-parity rather than pseudo-spin in infinite graphene. The perfect transmission in the case of head-on incidence is replaced by perfect transmission at the center of the ribbon and the chirality is interpreted as the projection of the pseudo-parity on momentum at different corners of the Brillouin zone

Effects of optical polarization on hybridization of radiative and evanescent field modes

The effects of induced optical polarization by Dirac electrons in graphene on the hybridization of radiative and evanescent fields are found. Such effects result in a localized polarization field which significantly modifies an incident surface-plasmon-polariton (SPP) field. This yields a high sensitivity to local dielectric environments and provides an investigative tool for molecules or proteins selectively bound with carbons. A scattering matrix is utilized with varied frequencies in the vicinity of the surface-plasmon (SP) resonance for the increase, decrease, and even a full suppression of the polarization field, which enables accurate effective-medium theories to be constructed for Maxwell-equation finite-difference time-domain methods. Moreover, double peaks in the absorption spectra for hybrid SP and graphene-plasmon modes are significant only with a large conductor plasma frequency, but are overshadowed by a round SPP peak at a small plasma frequency as the graphene is placed close to the conductor surface. These resonant absorptions facilitate polariton-only excitations, leading to polariton condensation for a threshold-free laser

The problem of storage of solid waste in permafrost

The specifics of solid waste storage in permafrost were analyzed. The main types of impact of the waste on the natural environment and frozen soils were determined as mechanical, physicochemical, load, and thermal. The research allowed us to define eight main types of waste storage in the permafrost zone, which were different both in terms of waste accumulation and in terms of their impact on the environment in general and the permafrost in particular. These were: industrial waste storage facilities (slag, sludge and tailing dumps, ash dumps); dumps of rock in sites of mining; household waste accumulators; dumps of wood processing waste in the centers of the timber industry; abandoned territories resulting from a decrease in the population of Northern settlements; storage areas for tanks with residues of fuels and lubricants; tank farms for storing petroleum products in settlements and cities of the North; storage areas for contaminated snow exported from built-up areas. Pollution of waste territories and destruction of many ecosystems as a result of waste storage were caused by use of imperfect technologies for the extraction and processing of raw materials, the ‘legacy’ of past years with disregard to the environmental conditions, the lack of special standards for the storage of garbage and by-product industrial materials, undeveloped methods of waste disposal in harsh climatic conditions

Effects of optical polarization on hybridization of radiative and evanescent field modes

The effects of induced optical polarization by Dirac electrons in graphene on the hybridization of radiative and evanescent fields are found. Such effects result in a localized polarization field which significantly modifies an incident surface-plasmon-polariton (SPP) field. This yields a high sensitivity to local dielectric environments and provides an investigative tool for molecules or proteins selectively bound with carbons. A scattering matrix is utilized with varied frequencies in the vicinity of the surface-plasmon (SP) resonance for the increase, decrease, and even a full suppression of the polarization field, which enables accurate effective-medium theories to be constructed for Maxwell-equation finite-difference time-domain methods. Moreover, double peaks in the absorption spectra for hybrid SP and graphene-plasmon modes are significant only with a large conductor plasma frequency, but are overshadowed by a round SPP peak at a small plasma frequency as the graphene is placed close to the conductor surface. These resonant absorptions facilitate polariton-only excitations, leading to polariton condensation for a threshold-free laser

Влияние технологических особенностей на чувствительность сенсоров на основе ферромагнитных структур

Main urgent problems of the magnetic devices and primary converters development based on the mag- netoresistive structures are the sensitivity improvement and thermal stability. The sensitivity was de- termined as the ratio of the magnitude of the output signal (imbalance voltage of the bridge under the action of magnetic field) to the magnetic field magnitude on the linear range of transfer characteris- tic. The investigated structures had a wide range of sensitivity values from 3.0 (mV/V)/(kA/m) to 9.4 (mV/V)/(kA/m), in the bias field value of 1 kA/m. It is established what the main influence on the sensitivity of the sensor has a width of permalloy strips. The distance between the barber pole has a substantially smaller effectОсновными актуальными задачами в разработке первичных преобразователей на основе магни- торезистивных структур являются повышение чувствительности и термостабильности. Чув- ствительность определяется как отношение величины выходного сигнала (напряжение разбалан- са мостовой схемы под действием магнитного поля) к величине магнитного поля на линейном участке передаточной характеристики. Были изготовлены магниторезистивные структуры с широким диапазоном чувствительности от 3.0 (мВ/В)/(кА/м) до 9,4 (мВ/В)/(кА/м) при зна- чении поля смещения 1 кА/м. Установлено, что основное влияние на чувствительность сенсора оказывает ширина полос пермаллоя. Расстояние между полосами имеет существенно меньший эффек