Generalized Elliott-Yafet theory of electron spin relaxation in metals: origin of the anomalous electron spin lifetime in MgB2

The temperature dependence of the electron-spin relaxation time in MgB2 is anomalous as it does not follow the resistivity above 150 K; it has a maximum around 400 K and decreases for higher temperatures. This violates the well established Elliot-Yafet theory of spin relaxation in metals. The anomaly occurs when the quasiparticle scattering rate (in energy units) is comparable to the energy difference between the conduction and a neighboring bands. The anomalous behavior is related to the unique band structure of MgB2 and the large electron-phonon coupling. The saturating spin relaxation is the spin transport analogue of the Ioffe-Regel criterion of electron transport.     

Mössbauer study on iron-polygalacturonate coordination compounds

⁵⁷Fe Mössbauer spectroscopy was used to determine the oxidation state and microenvironments of iron in the Fe-polygalacturonate compound prepared by a novel method from pectin. ICP analysis was applied to study the iron content of the coordination compounds. It was found that there are two ferrous and one ferric microenvironments in the compound. In the iron- polygalacturonate compound the ferrous forms occur dominantly. A model for the bonding of Fe in the polygalacturonate chains is proposed.     

The Dolbeault complex in infinite dimensions III. Sheaf cohomology in Banach spaces

We prove that the sheaf cohomology groups H ^q (Ω,?) vanish if Ω is a pseudoconvex open subset of a Banach space with unconditional basis, and q≥1. Oblatum 23-XII-1999 & 12-V-2000?Published online: 16 August 2000     

Thermal Decomposition of Hafnium Phosphate and Related Materials

The thermal decomposition of hafnium phosphate (both in amorphous and crystalline forms), molybdate and tungstate was investigated. Hafnium phosphate has a layered structure, that of molybdate and of tungstate are tetragonal one. On investigating these materials two main endothermic processes with mass loss were observed in the temperature range of 298–1023 K. These processes were identified as crystal and structural water loss of the materials. The total mass loss of hafnium phosphate, molybdate and tungstate was 11,35 and 6.0%, respectively. In the case of mixed hafnium-titanium salts various crystal water quantities were found, depending on the titanium content of the sample. This revised version was published online in July 2006 with corrections to the Cover Date.     

Vorticity‐velocity formulations of the Stokes problem in 3D

This work studies the three‐dimensional Stokes problem expressed in terms of vorticity and velocity variables. We make general assumptions on the regularity and the topological structure of the flow domain: the boundary is Lipschitz and possibly non‐connected and the flow domain may be multiply connected. Upon introducing a new variational space for the vorticity, five weak formulations of the Stokes problem are obtained. All the formulations are shown to lead to well‐posed problems and to be equivalent to the primitive variable formulation. The various formulations are discussed by interpreting the test functions for the vorticity (resp. velocity) equation as vector potentials for the velocity (resp. vorticity). Of the five sets of boundary conditions derived in the paper, three are already known, but only for domains with a trivial topological structure, while the remaining two are new. Copyright © 1999 John Wiley & Sons, Ltd.     

Mössbauer study of ionic and metallic states of electrodeposited Fe−Ni−P amorphous alloys

In this contribution we report cases in which we found ionic character of the amorphous state in electrodeposited Fe?Ni?P samples electroplated in a similar way but with different parameters to those exhibiting metallic amorphous character in their Mössbauer spectra. In particular, the room temperature transmission spectrum of an X-ray amorphous electrodeposited Fe₆₈Ni₂₃P₈ sample consists of two doublets with IS1=0.27 mm/s, QS1=0.51 mm/s, IS2=1.22 mm/s and QS2=2.54 mm/s parameters, where the latter is characteristic for Fe²⁺ state.     

On the parallel version of the successive approximation method for quasilinear boundary value problem

The convergence properties of the successive approximation method to solve a quasilinear two points boundary value problem is studied. The successive approximation method is used to solve the parallel/multiple version of the problem. Conditions which assure the convergence of the method and error bound are given.