Publications [#225906] of Kristen N. Collar

Papers Published
  1. MM Altarawneh, K Collar, CH Mielke, N Ni, SL Bud’ko, PC Canfield, Determination of anisotropic H c 2 up to 60 T in Ba 0.55 K 0.45 Fe 2 As 2 single crystals (December, 2008) [PhysRevB.78.220505] .

    The radio frequency penetration depth was measured in the superconductor (Ba0.55K0.45)Fe2As2 under pulsed magnetic fields extending to 60 T and down to 14 K. Using these data we are able to infer a Hc2(T), H-T phase diagram, for applied fields parallel and perpendicular to the crystallographic c axis. The upper critical-field curvature is different for the respective orientations, but they each remains positive down to 14 K. The upper critical-field anisotropy is moderate, ≈3.5 close to Tc, and drops with the decrease in temperature, reaching ≈1.2 at 14 K. These data and analysis indicate that (i) (Ba0.55K0.45)Fe2As2 anisotropy diminishes with temperature and has an unusual temperature dependence and (ii) Hc2(T=0) for this compound may easily approach fields of 75 T.