Radiative properties of Zeeman components of atomic multiplets: Magnetically induced decay of metastable 3 P 2 and 3 P 0 states of inert gases

It is shown that the magnetic field induces the radiative decay of metastable states of inert gases by mixing them with resonant sublevels of the lowest multiplet. The polarization and frequency structures of the “forbidden” lines induced by the magnetic field are determined, and the dependence of the intensity of π and σ components of these lines on the magnetic field is calculated. The effect is totally governed by the paramagnetic atom-field interaction, and the influence of the diamagnetic interaction is insignificant.     

The growth and domain structure of YBa2Cu3Ox films on neodymium gallate substrates with a deviation of the normal to the surface from the [110] direction in NdGaO3

The growth, crystal structure, and electrophysical properties of YBa₂Cu₃O_x (YBCO) epitaxial films grown with and without a CeO₂ epitaxial sublayer on NdGaO₃ (NGO) substrates with the normal to the surface deviating from the [110] axis by 5° to 26.6° around the [001] axis are investigated. It is shown that the orientation of YBCO epitaxial films grown on such substrates is determined by the existence of symmetry-equivalent directions in the substrate and in the CeO₂ layer, as well as by the rate of film deposition. For a high deposition rate, YBCO films grow on the CeO₂ sublayer in the [001] orientation irrespective of the orientation of the substrate and the sublayer. It was found that when the angle of deviation of the substrate plane is from the (110) NGO plane, twinning of one or both twinning complexes in YBCO may be suppressed.     

Magnetic and Resistive Properties of Magnetite/Iridate Heterostructures

Journal of Experimental and Theoretical Physics - A technique is developed to grow epitaxial heterostructures consisting of strontium iridate (SrIrO3) and lanthanum–strontium manganite...     

The state of strain in a semi-infinite plate with edge slots

An approximate method is given for determining the stress distribution in a semi-infinite plate weakened by several closely spaced edge slots with complicated shapes. The method is based on representing the displacement vector as the superposition of four types of singular solution in the planar theory of elasticity for a half-plane, with the solutions continuously distributed over rectilinear segments at the plate boundary, which are completely contained within the slots. Numerical results are given for two slots in a half-plate under tension when one of the slots is a half-ellipse and the other is a half-circle and when both slots are of the same shape and are formed by two quarter circles joined by a segment of the common tangent.Translated from Teoreticheskaya i Prikladnaya Mekhanika, No. 20, pp. 112–116, 1989.     

Andreev states and shot noise in bicrystal junctions of cuprate superconductors

Experimentally observed features of the electrical and noise characteristics of bicrystal junctions of cuprate superconductors, such as linearity of the critical current density versus square root of the junction transparency and increase in the spectral density of shot noise for small bias voltages (below the superconducting gap), indicate that the superconducting current in cuprate bicrystal junctions is determined by the passage of quasi-particles through a potential barrier at the superconductor boundaries. This process involves bound states appearing as a result of multiple Andreev reflections in superconductors with dominant wavefunction components of the d _x ² ? _y ² symmetry type. At the same time, interpretation of the experimental current-phase and current-magnetic field curves requires that the character of faceting at the bicrystal junctions would be also taken into account.     

Thermoelectric properties of high-pressure silicon phases

The thermo emf in Czochralski-grown silicon single crystals (Cz-Si) was experimentally studied in a range of pressures up to 20 GPa. The pressure dependences revealed phase transitions in the metallic phase of silicon, which passed from tetragonal to orthorhombic and then to hexagonal lattice. The high-pressure silicon phases, as well as the metallic high-pressure phases in A_NB_8?N semiconductors, possess conductivity of the hole type. As the pressure decreases, the emf behavior reveals transitions to the metastable phases Si-XII and Si-III. Preliminary thermobaric treatment of the samples at a pressure of up to 1.5 GPa and a temperature of T=50–650°C influences the thermoelectric properties of Cz-Si at high pressures.     

Superconducting current in hybrid heterojunctions of metal-oxide superconductors: Size and frequency dependences

We have detected experimentally considerable deviations of the frequency dependences of the Shapiro step amplitudes and the critical current of Nb/Au/YBa₂Cu₃O_x thin-film hybrid Josephson heterojunctions prepared on YBa₂Cu₃O_x metal-oxide superconductor films with a tilted c axis from the regularities inherent in Josephson junctions of traditional superconductors with an s-symmetry of the order parameter. It is shown that possible formation of “splintered” fluxons with a size λ_s<λ_J due to faceting of the interface and formation of a chain of nanosize 0 and π junctions must be taken into account in describing processes in lumped heterojunctions (whose size L is smaller than the Josephson penetration depth λ_J determined from the averaged value of the critical current density). For heterojunctions with a size λ_s < L < λ_J, a substantial decrease in the maximal amplitude of the first Shapiro step with increasing voltage (Josephson oscillation frequency) is observed at voltages much smaller than the energy gap in niobium (V « Δ_Nb/e); this effect is manifested most strongly when the size L is greater than λ_s. A fractional Shapiro step and a subharmonic detector response have been observed in the current-voltage characteristics of heterojunctions; the dynamic processes responsible for their emergence and indicating the presence of the second harmonic in the current-phase relation are studied. It is shown that the effect of interface faceting on the current-phase relation increases with a heterojunction size L>λ_s.