2003/05/31 by S. R. Park, S. M. Choi, D. C. Dender +2
Physics and Astronomy · #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevlett.91.167003
published as Phys. Rev. Lett. Vol.91, 167003 (2003) · 4 figures
arxiv created 2003/10/24 · arxiv updated 2009/11/30
We have used small-angle-neutron-scattering (SANS) and ac magnetic susceptibility to investigate the global magnetic field H vs temperature T phase diagram of a single crystal Nb in which a first-order transition of Bragg-glass melting (disordering), a peak effect, and surface superconductivity are all observable. It was found that the disappearance of the peak effect is directly related to a multicritical behavior in the Bragg-glass transition. Four characteristic phase boundary lines have been identified on the H-T plane: a first-order line at high fields, a mean-field-like continuous transition line at low fields, and two continuous transition line associated with the onset of surface and bulk superconductivity. All four lines are found to meet at a multicritical point.