Investigation of pinning and creep of the magnetic flux in the superconducting oxides on the basis of yttrium and erbium irradiated in a reactor

The dependences of the magnetic moment over the 4,2 K - 90 K temperature range and the peculiarities of the dynamic responce of rotating ceramic superconductor RBa2Cu3O7-δ (R=Y, Er) at T=4,2 K and 77 K to the applied torque upon the intensity of the transverse magnetic field H have been investigated. The jump-like magnetization increase and sharp enhancement of the pinning force were observed at T<40 K. The critical field Hc1 ∼ 30 Oe at T=77 K was determined by measuring the period of axially torsional oscillations of the superconducting specimen in the increasing magnetic field, and the influence of the earth's magnetic field frozen in the specimen on the character of these dependences was shown. The field dependences both of the dynamic and static counter-moments of pinning forces were determined, and the contribution of viscous friction forces affecting the magnetic vortex lines in the specimens at 4,2 K and 77 K was established