2002/06/30 by L. Lyard, P. Samuely, P. Szabo +15 · 1 citation
Physics and Astronomy · #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.66.180502
published as Phys. Rev. B 66 (2002), 180502 (R) · 6 pages, 5 figures
arxiv created 2002/09/18 · arxiv updated 2009/11/30
We report on specific heat, high magnetic field transport and ac-susceptibility measurements on magnesium diboride single crystals. The upper critical field Hc2 for magnetic fields perpendicular and parallel to the Mg and B planes is presented for the first time in the entire temperature range. A very different temperature dependence has been observed in the two directions which yields to a temperature dependent anisotropy with Γ∼ 5 at low temperatures and about 2 near Tc. A peak effect is observed in susceptibility measurements for H ∼ 2 T parallel to the c-axis and the critical current density presnts a sharp maximum for H parallel to the ab-plane.