Coulomb promotion of spin-dependent tunneling

We study transport of spin-polarized electrons through a magnetic single-electron transistor (SET) in the presence of an external magnetic field. Assuming the SET to have a nanometer size central island with a single-electron level we find that the interplay on the island between coherent spin-flip dynamics and Coulomb interactions can make the Coulomb correlations promote rather than suppress the current through the device. We find the criteria for this new phenomenon--Coulomb promotion of spin-dependent tunneling--to occur.     

Study of the polymorphic hexagonal-face-centered-cubic transformation in Cu2S

The results of a dynamic high-temperature x-ray diffraction investigation into the special characteristics of the hexagonal-fcc polymorphic transformation in Cu₂S are presented. Close to the phase-transformation temperature, two groups of superstructural reflections appear on the x-ray diffraction patterns, some of these being indexed in the 12H hexagonal lattice (Ramsdel) and others in the 14H lattice. The mechanism of the hexagonal — fcc phase transition in Cu₂S is considered as passing through the intermediate 12H and 14H polytypic structures by way of the successive accumulation of periodically disposed stacking faults. The effect of thermal cycling within the phase-transformation temperature range on the course of the actual transformation is verified.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 100–103, May, 1976.     

Investigation of quinones

The action of primary and secondary amines on 2-arylanthraquinonetriazoles results in substitution of the hydrogen atom in the 4 position to form 4-amino derivatives. The activity of 2-arylanthraquinonetriazoles in amination is less than that of the previously studied anthraquinone-1, 2,5-X-diazoles (X=O, S, Se). This is explained by the electron-donor effect of the aryl group in the 2 position and the lower degree of alternation of the bonds in the ring adjacent to the heteroring, which leads to a decrease in the effectiveness of transmission of the electron-acceptor effect to the reaction center in the 4 position.See [1] for communication XXVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1574–1580, November, 1971.     

Vibrational spectra and structure of N,N′-dinitroalkylenediamines

Conclusions The vibrational spectra of N,N-dinitroalkylenediamines O₂NNH(CH₂)_nNHNO₂ (n=1–3) were analyzed, and a frequency assignment was made.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1530–1532, July, 1986.     

Kinetics of cation-distribution variation in magnesium-manganese ferrites

Results are presented of an X-ray and neutron-diffraction investigation of the cation distribution as a function of the quenching temperature and isothermal-tempering duration for the ferrites Mg_1.093Mn_0.123Fe_1,784O_3.953 and Mg_0.812Mn_0.289Ni_0.062Fe_1.837O_3.998. To describe the kinetics of the ion redistribution in tempering, equations are proposed which satisfactorily describe the experimental curves. The magnetic moment, Curie temperature, and coercive force are investigated as a function of quenching temperature. The experimental data obtained are satisfactorily accounted for by Néel's theory of ferromagnetism.