Boundary Conditions at the Bulk–Aerogel Interface of Superfluid 3He-B

We study the interface between bulk and aerogel impregnated with ³ He-B. The magnetic susceptibility at the interface determines a boundary condition for the texture, which can be parameterized by the orbital vector L. We use Ginzburg–Landau theory to calculate the boundary condition assuming homogeneous aerogel and a sharp interface. Recent NMR measurements give reason to conjecture that L tends to be parallel to interface. Our numerical calculations confirm this conjecture in the Ginzburg–Landau (GL) regime. However, the orienting energy is one order of magnitude smaller than at a solid wall, and therefore can easily be overshadowed by a nearby wall.     

Radar sounding of hydroacoustic disturbances of the sea surface

The results of an experimental investigation of the interaction of hydroacoustic and electromagnetic fields at an air-water interface under laboratory conditions are reported. It is shown that this phenomenon can be used under natural conditions to transmit information from an underwater source to a receiver located in the atmosphere. Pis’ma Zh. Tekh. Fiz. 25, 64–73 (September 26, 1999)     

Identification of singular interfaces with Δ<Emphasis Type="Bold">g</Emphasis>s and its basis of the O-lattice

This article identifies singular interfaces according to singularity in terms of structural defects, including dislocations and ledges. Defect singularities are defined by the elimination of one or more classes of defects, which must be present in the vicinal interfaces. In addition to the three commonly classified structural interfaces, a new type of interface—the CS-coherent interface—is introduced. Singularities in dislocation and ledge structures have been integrated in the study of orientation relationships (OR). The dislocation structures are determined through the O-lattice theory, originally proposed by Bollmann. The basic concepts of the O-lattice and related formulas from the original theory and extended studies are briefly reviewed. According to the theory, singular interfaces exhibiting singularity in the dislocation structures have been identified. An interface that is singular with respect to the interface orientation must be normal to at least one Δg, a vector connecting two reciprocal points from different lattices. An interface that is singular also with respect to the OR must obey one or more Δg parallelism rules. The selection of proper Δgs for different preferred states of interfaces are explained. Identification of singular interfaces with measurable Δgs provides a convenient and effective approach to the interpretation of the observed facets and ORs. The ambiguity about the selection of the deformation matrix (A) for the O-lattice calculation and the advantage of the O-lattice approach over the approach using the Frank–Bilby equation for the calculation of the interfacial dislocations are clarified. Limitations of the present approach and further study are discussed.     

Influence of charge flow along a semiconductor surface on the nature of the multiplication coefficient in a silicon-wide-gap layer structure

It has been shown that the flow of mobile minority carriers along the semiconductor-wide-gap layer interface substantially influences the uniformity of the multiplication coefficient in an avalanche photodetector. Around inhomogeneities in the semiconductor substrate, a “dead zone” of fairly large area is formed, where the multiplication coefficient is several orders of magnitude lower than that on the remaining area of the device. Specific methods are proposed to improve the uniformity of the avalanche process in a semiconductor-wide-gap layer structure. Pis’ma Zh. Tekh. Fiz. 23, 72–76 (April 26, 1997)     

Oscillatory instability of the interface between conducting liquids in a normal electric field

It is shown that a new type of oscillatory instability, unlike the Tonks-Frenkel instability, may occur at a charged interface between two electrically conducting liquids in a perpendicular electrostatic field. Pis’ma Zh. Tekh. Fiz. 23, 41–44 (August 26, 1997)     

Instability induced in a relativistic plasma flux by the excitation of surface waves

An analysis is made of the instability of a plasma flux caused by the excitation of a new type of cylindrical surface electromagnetic waves at the interface between the flux and a stationary plasma. It is shown that, unlike the conventional case ε₁>0 and ε₂,<0, at the interface of a relativistic plasma beam there exist growing surface waves at frequencies corresponding to positive values of the permittivities on both sides of the discontinuity. For a given geometry and plasma density the critical parameter for the excitation of these waves is the wave radius of the flux. Pis’ma Zh. Tekh. Fiz. 23, 76–79 (March 12, 1997)     

Fine structure at the diffusion welded interface of Fe3Al/Q235 dissimilar materials

The interface of Fe ₃ Al/Q235 dissimilar materials joint, which was made by vacuum diffusion welding, combines excellently. There are Fe ₃ Al, FeAl phases and α-Fe (Al) solid solution at the interface of Fe ₃ Al/Q235. Aluminum content decreases from 28% to 1.5% and corresponding phase changes from Fe ₃ Al with DO ₃ type body centred cubic bcc structure to α-Fe (Al) solid solution with B2 type bcc structure. All phases are present in sub-grain structure level and there is no obvious brittle phases or micro-defects such as pores and cracks at the interface of Fe ₃ Al/Q235 diffusion joint.     

Enhancement of Rashba Spin–Orbit Interaction Due to Wave Function Engineering

We have demonstrated an enhancement of Rashba spin–orbit interaction (SOI) in In_0.53Ga_0.47As/In_0.7Ga_0.3As/In_0.53Ga_0.47As double-step structure in comparison with In_0.53Ga_0.47As normal quantum well. In the double-step structure, high electron probability density is located on the In_0.53Ga_0.47As/In_0.7Ga_0.3As heterointerface to enhance the interface contribution of Rashba SOI. The double-step structure is designed based on k⋅p formalism considering field and interface contributions separately. The Rashba parameter α calculated by the k⋅p formalism shows good agreement with the experimental value by analyzing weak antilocalization. The large carrier density dependence of α is due to the In_0.53Ga_0.47As/In_0.7Ga_0.3As heterointerface contribution as well as the energy-band bending in the In_0.7Ga_0.3As quantum well. The results of this study suggest that the precise control of interface and field contributions in Rashba SOI will make its application to semiconductor spintronics.     

Skew plane shock wave at the interface between two polytropic gases. A heavy-light gas system

In [Inzh.-Fiz. Zh., 72, No. 2, 208–215, 216–225 (1998)] the problem of break decay that occurs when a plane skew shock wave (SSW) arrives at the interface between two polytropic gases of different density (the polytrope indices of both gases remain constant in the entire region of interaction) from the side of the less dense of them is considered in detail. The change in the stationary shock-wave configuration with an increase in the angle of incidence from 0 to π/2 is tracked. In the present work, consideration is given to the development of a stationary shock-wave configuration in the case where the SSW emerges at the interface from the side of the more dense gas. Problems associated with boundary layers and mixing of contacting gases were not considered. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 802–806, July–August, 2000.     

Instability growth rate of a charged interface between immiscible electrically conducting liquids

It is shown by means of a numerical analysis of the dispersion equation that two types of aperiodic instability may occur at a charged planar interface between two viscous incompressible immiscible electrically conducting liquids, for which the growth rates increase or decrease, respectively as the conductivity ratio of the media increases. Pis’ma Zh. Tekh. Fiz. 23, 38–40 (August 26, 1997)     

Regular relief on a silicon surface as a structural defect getter

An investigation was made to determine how a regular relief on the silicon surface influences gettering in silicon-silicon-dioxide structures. The regular relief was created by a photolithographic technique before oxidation and comprised an orthogonal network of overlapping bands. The gettering was determined from the isothermal relaxation of the capacitance of a silicon-silicon-dioxide structure after switching from strong inversion to even stronger inversion. It is shown that a regular relief at the silicon-silicon-dioxide interface is an effective getter at a depth of several hundred micron. Pis’ma Zh. Tekh. Fiz. 25, 75–80 (January 12, 1999)     

Mechanism of initiation of acoustic emission in crystallization and melting of a substance. II

In[Inzh.-Fiz. Zh.,73,No. 5, 1064–1072 (2000)], the authors investigated one of the possible mechanisms of initiation of the acoustic effect of crystallization (melting) of substances, which was based on the assumption of a stepwise character of motion of the crystal-melt interface. In the present work, consideration is given to another mechanism of initiation of the acoustic effect of crystallization, which is based on the concept of possible enhancement of waves propagating in the liquid and in the crystal during the motion of their interface. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 5, pp. 1073–1079, September–October, 2000.     

Structural and electrical properties of swift heavy ion beam irradiated Co/Si interface

Synthesis of swift heavy ion induced metal silicide is a new advancement in materials science research. We have investigated the mixing at Co/Si interface by swift heavy ion beam induced irradiation in the electronic stopping power regime. Irradiations were undertaken at room temperature using 120 MeV Au ions at the Co/Si interface for investigation of ion beam mixing at various doses: 8 × 10¹², 5 × 10¹³ and 1 × 10¹⁴ cm⁻². Formation of different phases of cobalt silicide is identified by the grazing incidence X-ray diffraction (GIXRD) technique, which shows enhancement of intermixing and silicide formation as a result of irradiation.I–V characteristics at Co/Si interface were undertaken to understand the irradiation effect on conduction mechanism at the interface.     

Role of the pinch effect in a high-velocity metallic contact with a high current

Experimental evidence is presented in support of the hypothesis that the main factor determining the flow of physical processes on the interface of a sliding solid-state contact carrying a ∼0.1–1 MA/cm² current is the sausage-type MHD pinch instability. It leads to the appearance and explosive destruction of tightening (quasi) liquid constrictions connecting the contact surfaces, so that under magnetic-suspension conditions the sliding of the latter relative to one another is virtually contact-free on the greater portion of their area. Pis’ma Zh. Tekh. Fiz. 25, 89–94 (March 26, 1999)     

The dynamics of granular flow in an hourglass

We present experimental investigations of flow in an hourglass with a slowly narrowing elongated stem. The primary concern is the interaction between grains and air. For large grains the flow is steady. For smaller grains we find a relaxation oscillation (ticking) due to the counterflow of air, as previously reported by Wu et al. [Phys. Rev. Lett. 71, 1363 (1993)]. In addition, we find that the air/grain interface in the stem is either stationary or propagating depending on the average grain diameter. In particular, a propagating interface results in power-law relaxation, as opposed to exponential relaxation for a stationary interface. We present a simple model to explain this effect. We also investigate the long-time properties of the relaxation flow and find, contrary to expectations, that the relaxation time scale is remarkably constant. Finally, we subject the system to transverse vibrations of maximum acceleration Γ. Contrary to results for non-ticking flows, the average flow rate increases with Γ. Also, the relaxation period becomes shorter, probably due to the larger effective permeability induced by the vibrations. Received: 11 February 2000     

Prediction of interphase energies at the interface of heterogeneous metals

An approach is proposed to estimate the equilibrium values of the free interphase energies at the interface between two metals using data on their surface energies, heats of vaporization, electron work functions, and Hertzfeld parameters. Examples of the application of this technique to separating binary compositions containing iron are presented. Pis’ma Zh. Tekh. Fiz. 23, 85–89 (August 12, 1997)     

Evolution of the morphological structure of a two-dimensional cluster obtained with a linear microparticle trajectory in the diffusion-limited aggregation regime

Two-dimensional diffusion-limited aggregation of spherical microparticles was achieved experimentally as a result of their rectilinear motion (“ballistic aggregation”) at a “water-air” interface. A percolation cluster was obtained and the evolution of its morphological parameters was studied under compression. A change in the orientation of the cluster pores and a nonlinear coalescence and breakup process were observed. A fabrication technology is proposed for monolayer films similar to the Langmuir method. Pis’ma Zh. Tekh. Fiz. 25, 80–85 (December 12, 1999)     

Deformations and overlap of instability zones in the Mathieu-Hill equation

A numerical analysis of the Mathieu-Hill equation describing the time evolution of the amplitudes of capillary waves at the interface between two liquids, the upper moving relative to the denser lower liquid at a time-dependent velocity, is used to show that for certain values of the characteristic physical parameters, the zones of unstable amplitude growth become deformed and overlap to form a single, singly connected instability zone. Pis’ma Zh. Tekh. Fiz. 25, 13–18 (October 26, 1999)     

Allowance for the contribution of self-adsorption in estimates of the interphase energy in a solid-metal-own-melt system

An expression is verified to allow for the contribution of self-adsorption in the Young equation for the interface between a polycrystalline metal and its own melt using only two properties, the heat of fusion and the gram-atomic volume. The adequacy of this relation is established for precious and nontransition polyvalent metals. Pis’ma Zh. Tekh. Fiz. 24, 81–83 (March 12, 1998)     

Long-range gettering of microdefects in silicon single crystals during the formation of porous silicon layers on their surface and ion irradiation

Experimental data on the dissolution of microdefects in the near-surface regions of silicon single crystals during the electrochemical formation of porous silicon layers followed by argonion irradiation are presented. A decrease in the microdefect concentration is detected near the interface with porous silicon and near the opposite surface of the samples. Pis’ma Zh. Tekh. Fiz. 25, 50–54 (April 26, 1999)