Nonlinear absorption of radio waves in a noncollinear antiferromagnet

The nonlinear absorption of radio waves (200–800 MHz) in a noncollinear cubic antiferromagnet Mn₃Al₂Ge₃O₁₂ in an external magnetic field H ‖ [001] has been studied in the temperature range of 1.2–4.2 K. We attribute the observed dissipation of the electromagnetic energy to the parametric excitation of inhomogeneous surface waves at the boundaries of antiferromagnetic domains.     

TEM study of defects in AlxGa1−xN layers with different polarity

Transmission electron microscopy (TEM) studies of defects in Al_xGa_1?xN layers with various Al mole fractions (x=0.2, 0.4) and polarities were carried out. The samples were grown by ammonia molecular beam epitaxy on sapphire substrates and consisted of low-temperature AlN (LT-AlN) and high-temperature AlN (HT-AlN) buffer layers, a complex AlN/AlGaN superlattice (SL) and an Al_xGa_1?xN layer (x=0.2, 0.4). It was observed that at the first growth stages a very high density of dislocations is introduced in both Al-polar and N-polar structures. Then, at the interface of the LT-AlN and HT-AlN layers half-loops are formed and the dislocation density considerably decreases in Al-polar structures, whereas in the N-polar structures such a behavior was not observed.The AlN/AlGaN superlattice efficiently promotes the bend and annihilation of threading dislocations and respectively the decrease of the dislocation density in the upper Al_xGa_1?xN layer with both polarities.The lattice relaxation of metal-polar Al_0.2Ga_0.8N was observed, while N-polar Al_0.2Ga_0.8N did not relax. The dislocation densities in the N-polar Al_0.2Ga_0.8N and Al_0.4Ga_0.6N layers were 5.5×10⁹ cm^?2 and 9×10⁹ cm^?2, respectively, and in metal-polar Al_0.2Ga_0.8N and Al_0.4Ga_0.6N layers these were 1×10¹⁰ cm^?2 and 6×10⁹ cm^?2, respectively.Moreover, from TEM images the presence of inversion domains (IDs) in N-polar structures has been observed. The widths of IDs varied from 10 to 30 nm. Some of the IDs widen during the growth of the AlN buffer layers. The IDs formed hills on the surface of the N-polar structures.     

Bernoulli shifts and local density property

We consider the property LocDen for the squaring mapping into the space of all measure preserving transformations and into the space of mixing transformations. It is proved that Bernoulli shifts with infinite entropy do not possess this property.     

The kinetics and mechanism of reactions of aliphatic stable nitroxyl radicals with alkyl and peroxide radicals during styrene oxidation

A kinetic study (EPR, microvolumometry), quantum-chemical analysis (DFT B3LYP/6-31G*), and kinetic simulation of the antioxidant activity of aliphatic stable nitroxyl radicals during styrene oxidation was performed. The key reactions constituting the detailed mechanism of the process were analyzed. It was shown that the inhibiting action of nitroxyl radicals was caused by their reaction not only with alkyl radicals but also with substrate peroxy radicals, which resulted in the regeneration of nitroxyl radicals in chain-termination steps.     

Theory of sheath in a collisional multi-component plasma

The aim of this brief report is to study the behaviour of sheath structure in a multi-component plasma with dust-neutral collisions. The plasma consists of electrons, ions, micron size negatively charged dust particles and neutrals. The sheath-edge potential and sheath width are calculated for collisionally dominated sheath. Comparison of collisionless and collisionally dominated sheath are made.     

Synthesis of 4,5-Dialkyl-2-perfluoroaryl-1H-imidazol-1-ols and 4,5-Dimethyl-2-perfluoroaryl-1H-imidazoles

Russian Journal of Organic Chemistry - Aliphatic α-hydroxyamino oximes reacted with perfluoroaromatic aldehydes to give α-perfluoroaryl nitrones which underwent cyclization in acetic acid...     

Characteristics of the kinetics of photoreactions of polymethene dyes with radical polymerization

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 49, No. 4, pp. 573–580, October, 1988.     

On a new type of sublattice tipping in noncollinear antiferromagnets

An explanation is offered for the 30° tipping of sublattices which has been observed in the noncollinear antiferromagnet CsMnI₃. In contrast to the ordinary 90° spin flop, this phase transition is due to nonlinear and relativistic corrections to the susceptibility. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 11, 844–846 (10 December 1998)