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Superconducting Transition and Phase Diagram of Single Crystal MgB2

U. Welp·G. Karapetrov·W. K. Kwok·G. W. Crabtree·Ch. Marcenat·L. Paulius·T. Klein·J. Marcus·K. H. P. Kim·C. U. Jung·H. -S. Lee·B. Kang·S. -I. Lee
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Abstract

The superconducting phase diagram of MgB2 was determined from magnetization, magneto-transport and the first single-crystal specific heat measurements. A zero-temperature in-plane coherence length of 8 nm is determined. The superconducting anisotropy increases from a value around 2 near Tc to above 4.5 at 22 K. For H||c a pronounced peak effect in the critical current occurs at the upper critical field. Evidence for a surface superconducting state is presented for H||c which might account for the wide spread in reported values of the anisotropy.

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U. Welp, G. Karapetrov, W. K. Kwok, G. W. Crabtree, Ch. Marcenat, L. Paulius, T. Klein, J. Marcus, K. H. P. Kim, C. U. Jung, H. -S. Lee, B. Kang, S. -I. Lee. 2002-03-27. Superconducting Transition and Phase Diagram of Single Crystal MgB2. https://doi.org/10.1103/physrevb.67.012505

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