Thermodynamic Parameters of Single‐ or Multi‐Band Superconductors Derived from Self‐Field Critical Currents

Key questions for any superconductor include: what is its maximum dissipation‐free electrical current (its ‘critical current') and can this be used to extract fundamental thermodynamic parameters? Present models focus on depinning of magnetic vortices and implicate materials engineering to maximise pinning performance. But recently we showed that the self‐field critical current for thin films is a universal property, independent of microstructure, controlled only by the penetration depth. Here, using an extended BCS‐like model, we calculate the penetration depth from the temperature dependence of the superconducting energy gap thus allowing us to fit self‐field critical current data. In this way we extract from the T ‐dependent gap a set of key thermodynamic parameters, the ground‐state penetration depth, energy gap and jump in electronic specific heat. Our fits to 79 available data sets, from zinc nanowires to compressed sulphur hydride with critical temperatures of 0.65 to 203 K, respectively, are excellent and the extracted parameters agree well with reported bulk values. Samples include thin films, wires or nanowires of single‐ or multi‐band s ‐wave and d ‐wave superconductors of either type I or type II. For multiband or multiphase samples we accurately recover individual band contributions and phase fractions.     

Subject index

The structures of phosphorus-selenium glasses P_xPe_1?x with x=0 (pure selenium), 0.05, 0.15, 0.25, 0.40 and 0.50 have been investigated with neutron diffraction, extented, X-ray absorption fine structure measurements, and Raman and infrared spectroscopy. The behavior of the near-neighbor coordination at $\text{r～2.3}\text{A}\text{?}$ as a function of x suggests a picture in which P₄Se_n molecular units are linked together by Se atoms or chains. The diffraction patterns exhibit anomalous peaks at Q ～ 1.2Å which rise dramatically as P is added to the Se glass; these peaks can also be understood on a molecular picture. The Raman spectra at the larger P concentrations are characterized by series of relatively sharp peaks which also suggest molecular units and for x = 0.5 bear a close correspondence to the spectrum of crystalline P₄Se₃.     

Discounted cost optimality problem: stability with respect to weak metrics

We find inequalities to estimate the stability (robustness) of a discounted cost optimization problem for discrete-time Markov control processes on a Borel state space. The one stage cost is allowed to be unbounded. Unlike the known results in this area we consider a perturbation of transition probabilities measured by the Kantorovich metric, closely related to the weak convergence. The results obtained make possible to estimate the vanishing rate of the stability index when approximation is made through empirical measures.     

In silico consensus activity prediction,rational synthesis,and evaluation of antiglycation and antiplatelet activities of 3,6-disubstituted 1,2,4,5-tetrazines

Russian Chemical Bulletin - According to the in silico consensus activity prediction, a series of 3,6-disubstituted 1,2,4,5-tetrazines were synthesized as promising inhibitors of the Maillard...     

Structure of magnetic resonance in <Superscript>87</Superscript>Rb atoms

Magnetic resonance at the F_g = 1 \( \rightleftarrows \)F_e = 1 transition of the D₁ line in ⁸⁷Rb has been studied with pumping and detection by linearly polarized radiation and detection at the double frequency of the radiofrequency field. The intervals of allowed values of the static and alternating magnetic fields in which magnetic resonance has a single maximum have been found. The structure appearing beyond these intervals has been explained. It has been shown that the quadratic Zeeman shift is responsible for the three-peak structure of resonance; the radiofrequency shift results in the appearance of additional extrema in resonance, which can be used to determine the relaxation constant Γ₂. The possibility of application in magnetometry has been discussed.     

Electronic and infrared absorption spectra of linear and cyclic C6+ in a neon matrix

Electronic and infrared absorption spectra of mass-selected C6+, generated by dissociative electron impact ionization of C6Cl6 and C6Br6, have been recorded in 6 K neon matrices. Linear and cyclic forms of C6+ have been observed. The 2Pig<--Chi2Piu electronic transition of linear C6+ has its origin band at 646 nm whereas for the (2) 2B2<--Chi2A1 system of the cyclic isomer it lies at 570 nm. An infrared active fundamental mode in the ground electronic state of C6+ is observed at 2092 and 1972 cm(-1) for the linear and cyclic isomer, respectively.     

Edge resonance in an elastic semi-infinite cylinder

We study the three-dimensional elasticity operator in a semi-infinite circular cylinder subject to free boundary conditions, in the case of zero Poisson ratio. We prove, adapting the method from [15], i.e., by first finding an invariant subspace for the elasticity operator such that the essential spectrum has a strictly positive lower bound and then finding a test function in this space for which the variational quotient takes a value below the bottom of the essential spectrum, that there is an eigenvalue embedded in the continuous spectrum. Physically, an eigenvalue corresponds to a "trapped mode", that is, a harmonic oscillation localized near the edge. This effect, known in mechanics as the "edge resonance" has been extensively studied numerically and experimentally. Our paper extends the mathematical justification of such phenomena provided by [15] to a three-dimensional setting     

Pressure effects in ferromagnetic manganites and carrier scattering by disordered magnetic rare earths

The influence of hydrostatic pressure on the transport properties of (La_1-xR_x)_0.67Ca_0.33MnO₃ (,Tb) ferromagnetic manganites is investigated. The enhancement of the Curie temperature T_C under pressure agrees with previous data. In the paramagnetic range, the resistivity can be represented by a Mott localisation law, with a characteristic temperature T₀ decreasing with pressure. The variation of T_C with pressure is compared to the effect induced by replacing La by a magnetic rare earth in (La_1-xR_x)_0.67Sr_0.33MnO₃ manganites (, ..., Tm). The main effect is not related to the decrease of the mean radius of the cation, but to an additional scattering by the magnetic moment of the rare earth. Received: 15 May 1998 / Revised: 6 July 1998 / Accepted: 16 July 1998     

Radial limits of inner functions and Bloch spaces

Let be an inner function in the unit ball , . Assume that

where and is the radial derivative. Then, for all , the set has a non-zero real Hausdorff -content, and it has a non-zero complex Hausdorff -content.