Hydrogen isotope exchange in proton-conducting oxides during proton and deuteron irradiation

It has been found that during accelerator beam deuteron irradiation of a proton-conducting oxide containing protium H/D isotope exchange between beam ions and dissolved ions takes place. This isotope exchange was also observed during high-energy proton irradiation of the oxide containing dissolved deuterium atoms. These results provide evidence to a new type of hydrogen isotope exchange. Any appreciable effects of conjugate diffusion of hydrogen and oxygen ions and of the interface processes on the isotope exchange rate were eliminated. In this type of exchange the rate of replacement of H⁺ by D⁺ and of D⁺ by H⁺ was determined only by the properties of the crystal. The discovered effect was used in our study to obtain experimental data characterizing the dynamic and equilibrium behavior of hydrogen isotopes in the oxide BaZr_0.9Y_0.1O_{3 ? δ}.     

Ab initio calculation of the deformation potentials for intervalley phonons in silicon

The fully self-consistent first-principles calculations of electron scattering from short-wavelength phonons between lower valleys in the conduction band of a silicon crystal are carried out for the first time. The calculations of the lattice constant, the electron and phonon spectra, and the scattering probabilities are performed in the framework of a unified approach within the electron density functional theory. The theory contains no phenomenological assumptions regarding the relative position of minima in the conduction band, effective masses of carriers, interatomic forces, and scattering probabilities. The electron-phonon coupling constants (deformation potentials) for symmetry-allowed f and g transitions are calculated. The calculated constants lie in the range of values measured in different experiments involving intervalley transitions in silicon.     

Ab initio calculations of the deformation potentials for intervalley phonon-assisted transitions in АIIIВV crystals with sphalerite structure

Completely self-consistent ab initio calculations of scattering of electrons between the lowest minima of the conduction band by short-wavelength phonons are performed for the first time for a group of А ^III В ^V semiconductor crystals. The structure constants, electron and vibrational spectra, and probabilities of scattering are calculated for the crystals from unified positions within the electronic density functional method. The theory does not involve any phenomenological assumptions on positions of minima in the conduction band, effective carrier masses, interatomic forces, or scattering probabilities. The electron-phonon coupling constants (the deformation potentials) for actual Γ−X, Γ−L, and X−L transitions for scattering between the nonequivalent X−X and L−L valleys in the conduction bands of AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, and InSb crystals with sphalerite structure are calculated. Results obtained are compared with theoretical calculations within the phenomenological rigid ion model and with those performed by the selfconsistent frozen phonon method.     

The Vaidya problem in conformally flat Stäckel spaces of type (1.1)

The problem of classification of conformally flat radiation spaces admitting full separation of variables in the Hamilton–Jacobi equation is considered. The Vaidya problem for conformally flat St?ckel spaces of type (1.1) has been solved; the metrics and the radiation have been found in explicit form. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 12–14, January, 2009.     

Local ferromagnetic resonance imaging with magnetic resonance force microscopy

We report nanoscale scanned probe ferromagnetic resonance force microscopy (FMRFM) imaging of individual ferromagnetic microstructures. This reveals the mechanism for high spatial resolution in FMRFM imaging: the strongly inhomogeneous local magnetic field of the cantilever mounted micromagnetic probe magnet used in FMRFM enables selective, local excitation of ferromagnetic resonance (FMR). This approach, demonstrated here in individual permalloy disks, is straightforwardly extended to excitation of localized FMR modes, and hence imaging in extended films.     

Measurement of the probability of atomic capture and depolarization of negative muons in high-temperature superconductors

The possibility of investigating high-temperature superconductors (HTSC) by the μSR method with negative muons is discussed in the paper. The results of measurement of the probability of negative muon capture by oxygen and residual polarization of muons in the 1s-state of oxygen in some HTSC at room temperature are reported.     

Experimental bounds on parameters of spin-spin interaction in gauge theory of gravitation

The contribution of the pseudovector component of the torsion for the hyperfine splitting of the hydrogen atom is considered. The calculations are made in the framework of a Poincaré gauge theory of gravitation with the most general Lagrangian quadratic in the curvature and torsion and containing a term of Hilbert-Einstein type. Some estimates of the model are obtained.Section of Theoretical Problems, USSR Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 90, No. 2, pp. 307–312, February, 1992.