Vortex phase diagram of pristine and irradiated Co-doped BaFe2As2

Vortex phase diagram is studied up to H = 170 kOe in a pristine and Xe (800 MeV, Bφ= 20 kOe) irradiated Ba(Fe0.925Co0.075)2As2 single crystals. In both samples, temperature dependence of resistivity (ϱ) and current (I)-voltage (V) characteristics are carefully measured with a voltage resolution better than 1 nV In the pristine sample, clear indication of vortex glass transition is obtained. Critical exponents in the pristine sample show little magnetic field dependence unlike the case for SmFeAsO0.85 crystal. Rather, it is similar to the case of YBa2Cu3O7−δ single crystals. In the irradiated sample, both vortex glass and Bose glass scalings give reasonable overlaps of I-V curves.