The dc-current destruction of superconducting state and hysteresis effects in Ba−K−Bi−O

The dc-current destruction of superconducting state in Ba−K−Bi−O was registered simultaneously both by measuring V–I characteristic and magnetic susceptibility χ. The experiments were carried out on the polycrystall samples in the temperature interval 1.5–4.2 K. The hysteresis of both characteristics was observed, the temperature dependencies of hysteresis value of V–I and c-I being quiet opposite. The nonmonotonic temperature dependence of I has been found. The observed effects can be explained in the framework of the model, according to which the special nonhomogeneous state can arise—the space structure of the alternate superconducting and insulating regions with Josephson tunnelling between the former.