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We examine the superconducting anisotropy $\gamma_c = (m_c / m_{ab})^{1/2}$ of a metallic high-$T_c$ superconductor MgB$_2$ by measuring the magnetic torque of a single crystal. The anisotropy $\gamma_c$ does not depend sensitively on the…

The angular and temperature dependence of the upper critical field Hc2 in MgB2 was determined from torque magnetometry measurements on single crystals. The Hc2 anisotropy gamma_H was found to decrease with increasing temperature, in…

Superconductivity · Physics 2009-11-07 M. Angst , R. Puzniak , A. Wisniewski , J. Roos , H. Keller , P. Miranovic , J. Jun , S. M. Kazakov , J. Karpinski

We investigated the magnetic anisotropy ratio of thin sputtered polycrystalline MgB2 films on MgO substrates. Using high magnetic field measurements, we estimated an anisotropy ratio of 1.35 for T=0 K with an upper critical field of 31.74 T…

Taking advantage of recent progress in neutron instrumentation and in the understanding of magnetic-field-dependent small-angle neutron scattering, here, we study the three-dimensional magnetization distribution within an isotropic Nd-Fe-B…

Muon-spin rotation spectroscopy has been used to measure the internal magnetic field distribution in NbSe2 for Hc1 << H < 0.25 Hc2. The deduced profiles of the supercurrent density indicate that the vortex-core radius in the bulk decreases…

The anisotropy of the magnetic excitations in BaFe$_2$As$_2$ was studied by polarized inelastic neutron scattering which allows one to separate the components of the magnetic response. Despite the in-plane orientation of the static ordered…

Superconductivity · Physics 2013-10-17 N. Qureshi , P. Steffens , S. Wurmehl , S. Aswartham , B. Büchner , M. Braden

Imaging of flux vortices in high quality MgB$_2$ single crystals has been successfully performed in a commercial Field Emission Gun-based Transmission Electron Microscope. In Cryo-Lorentz Microscopy, the sample quality and the vortex…

We present a theoretical survey of magnetocrystalline anisotropies in (Ga,Mn)As epilayers and compare the calculations to available experimental data. Our model is based on an envelope function description of the valence band holes and a…

Materials Science · Physics 2015-05-13 J. Zemen , J. Kucera , K. Olejnik , T. Jungwirth

Using small-angle neutron scattering we have studied the vortex lattice in superconducting MgB$_2$ with the magnetic field applied along the $c$-axis, doped with either manganese or carbon to achieve a similar suppression of the critical…

We have studied anisotropic magnetoresistance (MR) and magnetization with rotating magnetic field (B) within $CuO_2$ plane in lightly doped AF $Nd_{2-x}Ce_xCuO_{4}$. \emph{A giant anisotropy} in MR is observed at low temperature below 5 K.…

Superconductivity · Physics 2009-11-13 T. Wu , C. H. Wang , G. Wu , D. F. Fang , J. L. Luo , G T. Liu , X. H. Chen

Using approximate analytical and new numerical solutions of the conventional Ginzburg-Landau equations we calculate the small angle neutron scattering cross-section and the variance of the field distribution as measured by muon-spin…

Superconductivity · Physics 2016-08-31 A. Yaouanc , P. Dalmas de Reotier , E. H. Brandt

Using analytical expressions for the magnetization textures of thin submicron-sized magnetic cylinders in vortex state, we derive closed-form algebraic expressions for the ensuing small-angle neutron scattering (SANS) cross sections.…

Mesoscale and Nanoscale Physics · Physics 2016-04-27 Konstantin L. Metlov , Andreas Michels

Neutron scattering measurements were performed to investigate magnetic excitations in a single-crystal sample of the ternary iron arsenide BaFe2As2, a parent compound of a recently discovered family of Fe-based superconductors. In the…

Strongly Correlated Electrons · Physics 2009-02-28 K. Matan , R. Morinaga , K. Iida , T. J. Sato

A large anisotropy in the upper critical field (H$_{C2}$) is observed for MgB$_{2}$ films grown in situ by a pulsed laser deposition process involving growth and annealing of Mg and B multilayers. Measurements of resistivity as a function…

Superconductivity · Physics 2007-05-23 S. R. Shinde , S. B. Ogale , A. Biswas , R. L. Greene , T. Venkatesan

We report zero-field inelastic neutron scattering experiments on a deuterated powder sample of Mn12-Acetate consisting of a large number of nominally identical spin-10 magnetic clusters. Our resolution enables us to see a series of peaks…

Theory of hole magnetization Mc in zinc-blende diluted ferromagnetic semiconductors is developed relaxing the spherical approximation of earlier approaches. The theory is employed to determine Mc for (Ga,Mn)As over a wide range of hole…

Materials Science · Physics 2009-09-29 C. Sliwa , T. Dietl

We have investigated the magnetic microstructure of two-phase Fe-Nb-B~based Nanoperm alloys using unpolarized small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). Our SANS analysis reveals a significantly large…

Materials Science · Physics 2024-05-24 Venus Rai , Ivan Titov , Michael P. Adams , Kiyonori Suzuki , Joachim Kohlbrecher , Andreas Michels

We use a set of magnetohydrodynamics (MHD) simulations of fully-developed (driven) turbulence to study the anisotropy in the velocity field that is induced by the presence of the magnetic field. In our models we study turbulence…

Astrophysics of Galaxies · Physics 2015-05-30 Alejandro Esquivel , Alex Lazarian

The experimental study of magnetic flux penetration under crossed magnetic fields in Bi2212:Pb single crystal performed by magnetooptic technique (MO) reveals remarkable field penetration pattern alteration (flux configuration change) and…

Superconductivity · Physics 2009-11-10 L. S. Uspenskaya , A. B. Kulakov , A. L. Rakhmanov

Anisotropic properties of superconducting MgB2 obtained by torque magnetometry are compared to theoretical predictions, concentrating on two issues. Firstly, the angular dependence of Hc2 is shown to deviate close to Tc from the dependence…

Superconductivity · Physics 2009-11-10 M. Angst , D. Di Castro , R. Puzniak , A. Wisniewski , J. Jun , S. M. Kazakov , J. Karpinski , S. Kohout , H. Keller