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Magnetohydrodynamic Simulation of Tungsten Wire in Wire-Array Z Pinch
Kim, D.-K.,Chittenden, J. P.,Lebedev, S. V.,Marocchino, A.,Suzuki-Vidal, F. WILEY-VCH Verlag 2010 Contributions to plasma physics Vol.50 No.2
<P>The magnetohydrodynamic behavior of tungsten wire ablating in wire-array Z pinch discharge on MAGPIE is simulated in a two-dimensional fine-grid domain using the GORGON code. A nonideal resistivity model has been implemented in the simulation to obtain plasma transport coefficients in the high density regime along with a screened hydrogenic model to calculate the radiative cooling. Starting from the initial state of warm dense plasma, the evolution of ablated wire is demonstrated to show its explosion and implosion dynamics as a function of discharge time and then the computed profile of electron density is compared with the contour lines reproduced from the measurement by a laser interferometer during the early stage of discharge. The comparison overall shows a fair agreement in terms of the magnitude and the profile shape while some discrepancies can be attributed to the simplified description of the internal wire core physics (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Moshnyaga, V.,Belenchuk, A.,Hü,hn, S.,Kalkert, C.,Jungbauer, M.,Lebedev, O. I.,Merten, S.,Choi, K.-Y.,Lemmens, P.,Damaschke, B.,Samwer, K. American Physical Society 2014 Physical review. B, Condensed matter and materials Vol.89 No.2
A commonly believed picture of colossal magnetoresistance (CMR) effect is related to a first-order phase transition and electronic phase separation with coexisting ferromagnetic metallic and antiferromagnetic insulating phases. However, the underlying mechanism, i.e., the characteristic energy scale of the interacting phases and their spatial extent, is still under debate. Here we present experimental evidence on the existence of an effective antiferromagnetic coupling between the ferromagnetic nanodomains in epitaxial thin films of a classical CMR material (La1-yPry)(0.67)Ca0.33MnO3 with Pr doping, y = 0.375 and 0.4. This coupling yields to peculiar low-field CMR behavior with magnetic hysteresis and slow resistance relaxation, both induced by the magnetization reversal. The coercive field obeys a square-root temperature dependence for T << T-C and increases anomalously close to the phase transition. We modeled the magnetic structure within the phase-separation scenario as an assembly of single-domain ferromagnetic nanoparticles, antiferromagnetically coupled (pinned) by correlated Jahn-Teller polarons. The concentration of polarons increases drastically close to phase transition as indicated by the third harmonic of the electrical conductivity as well as Raman spectroscopy.
The superconducting bismuth-based mixed oxides
E.V.Antipov,N.R.Khasanova,J.S.Pshirkov,S.N.Putilin,C.Bougerol,O.I.Lebedev,G.VanTendeloo,A.N.Baranov,Y.W.Park 한국물리학회 2002 Current Applied Physics Vol.2 No.5
The present paper describes the synthesis, characterization of mixed-valence bismuthates with three- or two-dimensional per-ovskite-like structures and structural criteria that inuence superconductivity in these compounds.Single-phase samples of Sr1. xKxBiO3 were prepared for the broad range of K-content: 0:256 x6 0:65. For these bismuthates thesymmetry of the structure changes from monoclinic to orthorhombic and nally to tetragonal upon increasing the K-content thusTc ¼ 12K exists in the narrow range (x . 0:50.6) within the stability eld of the tetragonal phase (0:336 x6 0:65), when the three-dimensional octahedral framework has close to the ideal perovskite structure arrangement.The layered type (Ba,K)3Bi2O7 and (Ba,K)2BiO4 bismuthates belonging to the Anþ 1BnO3nþ 1 homologous series were investi-gated. Buckling of the (BiO2 n ¼ 2 member occurs due to the ordering of alkaline- and alkaline-earthcations between two independent positions. The formation of the one-layer bismuthate was revealed by Electron Microscopy andXRPD studies. Both types of compounds are considered to be possible candidates for new superconducting materials amongbismuthates.. 2002 Published by Elsevier Science B.V.