Spatial inhomogeneity of the interaction between bistable ferromagnetic wires

An experimental study and a theoretical calculation are presented of the hysteresis loop of two bistable ferromagnetic wires. A new effect—an asymmetry of the shift of the switching field at the first and the second Barkhausen jump—is found experimentally. The effect is explained as a consequence of the spatial dependence of the stray field. It is also reproduced within our recent calculation of the stray field from the magnetisation profile. Theoretical results qualitatively agree with the experimental data.     

Peculiarities of Quadrupolar Relaxation in Electrolyte Solutions

Peculiarities of quadrupolar relaxation in electrolyte solutions were established via comparison of the data obtained from proton and deuteron resonances. It has been shown that quadrupole coupling constants (QCC) of deuterons depend not only on internal electron structure of molecule or ion, but on solution structure as well. To interpret the experimental results quantum-chemical calculations of QCC of deuterons in different molecular complexes simulating different solution substructures were carried out. Density functional theory (DFT) method with hybrid B3LYP functional was used for all calculations.     

Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films

We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La_0.7Ca_0.3MnO₃ (LCMO) and YBa₂Cu₃O_7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO₃ (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on the LAO (control) and LCMO side of the substrate. Critical current, I _c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed that while the control side showed a J _c of ∼ 2 × 10⁶ A/cm², the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J _c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of J _c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length has been quantified. A control experiment carried out with LaNiO₃ deposited by PLD on YBCO did not show any evidence of self-injection.     

Solvation of cations in the LiNO3-Ca(NO3)2-H2O system at 25°C. A molecular dynamics simulation study

A series of solutions of the ternary LiNO₃-Ca(NO₃)₂-H₂O system is simulated under standard conditions by means of classical molecular dynamics (MD). Several variants of the potentials of interparticle interactions predicting different structures and compositions of the lithium cation hydration shell are used in the calculations. The coordination numbers of ions, the mean residence times of water molecules and nitrate anions in the solvation shells of cations, and the self-diffusion coefficients of solution components are estimated for all of the investigated systems. The structural features of the solvation shells of cations in multicomponent aqueous solutions are described on the basis of the obtained data.     

Effect of quantum entanglement on Aharonov-Bohm oscillations, spin-polarized transport and current magnification effect

We present a simple model of transmission across a metallic mesoscopic ring. In one of its arm an electron interacts with a single magnetic impurity via an exchange coupling. We show that entanglement between electron and spin impurity states leads to reduction of Aharonov-Bohm oscillations in the transmission coefficient. The spin-conductance is asymmetric in the flux reversal as opposed to the two-probe electrical conductance which is symmetric. In the same model, in contradiction to the naive expectation of a current magnification effect, we observe enhancement as well as suppression of this effect depending on the system parameters. The limitations of this model to the general notion of dephasing or decoherence in quantum systems are pointed out.     

Eigenvalue Asymptotics of the Stokes Operator for Fractal Domains

The leading asymptotic term for the function that counts theeigenvalues of the Stokes operator is determined for fairlygeneral underlying bounded domains. Moreover, the remainderis estimated in terms of the fractality of the boundary of thedomain. The results obtained resemble corresponding ones forthe Dirichlet Laplacian. 1991 Mathematics Subject Classification:35P20.     

The interaction of the theophylline metastable phase with water vapor

The conditions of hydration of the stable and metastable theophylline phases were determined. Two-phase metastable phase/monohydrate and stable phase/monohydrate equilibrium pressures were measured at 25, 30, and 35°C. The metastable phase began to react with water vapor at lower relative humidities than the stable phase. Processes that occurred with the metastable and stable theophylline phases over various water pressure ranges were considered. The metastable phase exhibited an unusual behavior at 25°C and relative humidity 47%. At constant water vapor pressure and temperature, theophylline was initially hydrated and then lost water and again became anhydrous. Two consecutive processes occurred in the system, the formation of theophylline monohydrate from the metastable phase and its decomposition to the stable phase. The ratio between the rates of these processes determined the content of the monohydrate at the given time moment.     

Transfer measurements for the Ti+Ni systems at near barrier energies

Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies. Coupled channel calculations incorporating couplings to 2⁺ and 3⁻ states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer were carried out for ^46,48Ti+⁶¹Ni systems. The present paper gives the results of these studies.