Determination of superconducting anisotropy from magnetization data on random powders as applied to LuNi${}_2$B${}_2$C, YNi${}_2$B${}_2$C and MgB${}_2$

Abstract

The recently discovered intermetallic superconductor MgB2 appears to have a highly anisotopic upper critical field with Hc2(max)/Hc2(min} = γ> 5. In order to determine the temperature dependence of both Hc2(max) and Hc2(min) we propose a method of extracting the superconducting anisotropy from the magnetization M(H,T) of randomly oriented powder samples. The method is based on two features in dM/dT the onset of diamagnetism at Tc(max), that is commonly associated with Hc2, and a kink in dM/dT at a lower temperature Tc(min). Results for LuNi2B2C and YNi2B2C powders are in agreement with anisotropic Hc2 obtained from magneto-transport measurements on single crystals. Using this method on four different types of MgB2 powder samples we are able to determine Hc2(max)(T) and Hc2(min)(T) with γ\approx 6.

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Cited by in corpus (46)

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• Limits of the upper critical field in dirty two-gap superconductors
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• An Overview of the Basic Physical Properties of MgB${}_2$
• Current percolation and anisotropy in polycrystalline MgB${}_2$
• New Materials Physics
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• Temperature dependence and anisotropy of the bulk upper critical field H_c2 of MgB_2
• Neutron Irradiation of MgB2 Bulk Superconductors
• Anisotropies of the lower and upper critical fields in MgB${}_2$ single crystals
• Anisotropy of the upper critical field in superconductors with anisotropic gaps. Anisotropy parameters of MgB2
• Superconducting Transition and Phase Diagram of Single Crystal MgB2
• The different development of the anisotropic upper critical field in MgB2 by aluminum and carbon doping
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• Temperature-dependent $H_{c2}$ anisotropy in MgB${}_2$ as inferred from measurements on polycrystals
• Anisotropy parameters of superconducting MgB${}_2$
• Superconductivity of magnesium diboride
• Scanning Tunneling Spectroscopy on Single Crystal MgB2
• Thermally-activated current transport in MgB_2 films
• Surface Contribution to the Superconducting Properties of MgB2 Single Crystals
• Strong Coupling and Double Gap Density of States in Superconducting MgB2
• Effect of damage by 2-MeV He ions and annealing on Hc2 in MgB2 thin films
• Influence of Al doping on the critical fields and gap values in magnesium diboride single crystals
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• Anisotropic Connectivity and its Influence on Critical Current Densities, Irreversibility Fields, and Flux Creep in In-Situ-Processed MgB2 Strands
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• ${}^{11}$B NMR detection of the magnetic field distribution in the mixed superconducting state of MgB${}_2$
• Angular-dependent upper critical field of overdoped Ba(Fe${}_{1-x}$Ni${}_x$)${}_2$As${}_2$
• A magnetization and ${}^{11}$B NMR study of Mg${}_{1-x}$Al${}_x$B${}_2$ superconductors
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• Surface states and their possible role in the superconductivity of MgB2
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• Ab initio calculations of H${}_{c2}$ for Nb, NbSe2, and MgB2
• Theory for phonon-induced superconductivity in MgB${}_2$
• Effects of the Two- Gap Nature on the Microwave Conductivity of 39 K Polycrystalline MgB2 Films
• Small-angle neutron scattering study of the vortex lattice in superconducting LuNi2B2C
• Magnetic Field Induced Density of States in Superconducting MgB${}_2$: Measurement of Conduction Electron Spin-Susceptibility
• Anisotropic thermal expansion and magnetostriction of YNi${}_2$B${}_2$C single crystals
• Anisotropy of Electrical Transport and Superconductivity in Metal Chains of Nb2Se3
• Microwave Surface Resistance and Upper-Critical-Field Anisotropy of MgB2 Superconductor
• Magnetic field induced orientation of superconducting MgB${}_2$ crystallites determined by X-ray diffraction