Vortex lattice reorientation and anisotropy in MgB<sub>2sub>&ndash;&ndash;effects of two-band superconductivity

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• 作者：Dewhurst ; C.D. ; Cubitt ; R. ; Eskildsen ; M.R. ; Jun ; J. ; Kazakov ; S.M. ; Karpinski ; J.
• 关键词：74.25.Qt ; 74.70.Ad ; 61.12.Ex ; Small-angle neutron scattering ; Vortex lattice ; MgB<sub>2sub>
• 刊名：Physica C
• 出版年：2004
• 期刊代码：80_09214534
• 类别：ms
• 出版时间：May 1, 2004
• 卷：404
• 期：1-4
• 页码：135-139
• 文件大小：325 K

摘要

We present small-angle neutron scattering (SANS) measurements of the vortex lattice (VL) in single crystal MgB<sub>2sub>&ndash;&ndash;a two-band superconductor. Bragg diffraction of neutrons visualizes the structure and orientation of the VL while the scattered intensity probes the super-carrier density. Superconductivity in the π-band is rapidly suppressed with increasing field with a corresponding decrease in scattered intensity and a re-orientation of the VL between 0.5 and 0.9 T. Both these observations are consistent with superconductivity in the π-band being weaker than in the σ-band (Δ<sub>πsub><Δ<sub>σsub>), and a changing influence of different parts of the Fermi surface determining the VL orientation. SANS measurements of the VL for fields applied at an angle to the c-axis allow the penetration depth anisotropy, γ<sub>λsub>, to be estimated.