Optical Hall conductivity of systems with gapped spectral nodes

We calculate the optical Hall conductivity within the Kubo formalism for systems with gapped spectral nodes, where the latter have a power-law dispersion with exponent n. The optical conductivity is proportional to n and there is a characteristic logarithmic singularity as the frequency approaches the gap energy. The optical Hall conductivity is almost unaffected by thermal fluctuations and disorder for n=1, whereas disorder has a stronger effect on transport properties if n=2

On a Theoretical Study of the Properties of Solutions of the Limit Problem for a Magnetically Noninsulated Diode

In this paper, we study the lower and upper bounds for solutions of the limit problem for the plane vacuum diode in the magnetic field in the statement by N. Ben Abdallah, P. Degond, and F. Mehats. This problem was finally set by physicists in the late 1980s and was extensively studied by numerous mathematicians in the 1990s.Досліджено нижні i вepxнi мєжі для розв'язків граничної задачi плоского вакуумного діода у магнітному полі у постановці Н. Бен Абдалла, П. Дегонда та Р. Мехаца. Ця задача була остаточно поставлена фізиками наприкінці 1980-х років i уважно досліджена багатьма математиками у 1990-х роках

Effect of strain relaxation on active-region formation in InGaN/(Al)GaN heterostructures for green LEDs

International audienceProcesses of active-region formation for green LEDs on the basis of multilayer strained InGaN/GaN nanoheterostructures have been studied. It is shown that the formation of structures of this kind is highly affected by elastic stress relaxation leading to a larger amount of indium incorporated into InGaN layers. For structures emitting in the blue spectral range, an increase in the number of quantum wells (QWs) from 1 to 10 does not lead to stress relaxation or to a shift of the emission wavelength, whereas for structures emitting in the green spectral range, raising the number of QWs from one to five causes a monotonic increase in the emission wavelength