Article

Superconducting transition and phase diagram of single-crystal MgB_ {2}

Department of Physics, Western Michigan University, Kalamazoo, Michigan, United States
Physical Review B (Impact Factor: 3.66). 01/2003; 67(1). DOI: 10.1103/PhysRevB.67.012505
Source: arXiv

ABSTRACT The superconducting phase diagram of MgB2 was determined from magnetization, magnetotransport, and single-crystal specific-heat measurements. A zero-temperature in-plane coherence length of 9.4 nm is determined. The superconducting anisotropy γ 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 that might account for the widespread in reported values of γ.

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